A metal atom catalyst synthesized in situ by ionizing radiation and its synthesis method

Abstract

This invention provides a metal atom catalyst synthesized in situ based on ionizing radiation and its synthesis method, comprising the following synthesis steps: adding a catalyst support and a metal salt to an ethanol solution, stirring at 50℃~70℃ for 1~4 h, and then filtering out the solid; vacuum drying the solid, then mixing it with an appropriate amount of isopropanol and deionized water in a centrifuge tube, removing the air from the centrifuge tube, and then irradiating it at an irradiation dose rate of 0.4~1.0 kGy / h for 6~25 h; filtering the irradiated mixture, and washing and vacuum drying the resulting solid to finally obtain the metal atom catalyst. The synthesis process provided by this invention is simple, low-cost, and significantly reduces the required irradiation dose. The prepared metal atom catalyst exhibits high metal single-atom dispersion and loading, providing an economical, efficient, and scalable method for the synthesis of carbon-supported multi-metal atom catalysts.

Description

Technical Field

[0001] This invention relates to the field of catalysts and their preparation technology, and in particular to a metal atom catalyst and its synthesis method based on in-situ synthesis by ionization irradiation. Background Technology

[0002] Advanced oxidation technologies (AORs), through the generation of active species, can effectively remove and even mineralize recalcitrant organic pollutants in water bodies, showing broad application prospects in the field of water treatment. The treatment efficiency of AORs depends on heterogeneous catalysts. To date, heterogeneous catalysts reported for use in AORs can be categorized into carbon materials, carbon-based materials, and metal compounds. Among these, carbon-supported metal atom catalysts have received widespread attention in the field of environmental catalysis due to their high metal atom utilization and excellent catalytic activity. To overcome the problem of limited metal active sites in carbon-supported metal atom catalysts, researchers have developed carbon-supported multi-metal atom catalysts. These catalysts increase the number of metal active sites and improve catalytic stability by utilizing intermetallic interactions.

[0003] Currently, common methods for preparing carbon-supported metal atom catalysts include chemical deposition, pyrolysis, and photocatalytic synthesis. However, these methods have certain drawbacks that limit the practical application of carbon-supported metal single atoms. For example, pyrolysis is currently the most widely used method for synthesizing carbon-supported metal atom catalysts. However, pyrolysis requires high temperatures, and due to the mutual attraction between metal single atoms during the pyrolysis process, it is difficult to achieve a uniform distribution of metal single atoms. When synthesizing multi-metal atom catalysts, complex precursors are usually required to complex different metal ions before pyrolysis. Even during pyrolysis, metal ion aggregation is still unavoidable, leading to the formation of metal nanoclusters or metal nanoparticles. How to reduce the temperature required for preparing carbon-supported metal atom catalysts, avoid metal ion aggregation during the preparation process, and achieve a uniform distribution of metal ions is crucial for the widespread application of carbon-supported metal atom catalysts in water treatment.

[0004] Ionizing radiation refers to radiation carrying enough energy to ionize atoms or molecules, freeing electrons in those atoms or molecules. Currently, ionizing radiation technology is widely used in food sterilization and material modification. When ionizing radiation acts on water, it causes radiolysis of water molecules, producing reactive species such as hydroxyl radicals, hydrated electrons, and hydrogen radicals. When other ions, such as metal ions, are present in the water, these reactive species can interact with the metal ions, causing oxidation or reduction. Therefore, ionizing radiation can be used to synthesize carbon-supported metal atom catalysts.

[0005] However, existing ionizing radiation methods for preparing carbon-supported metal atom catalysts still suffer from problems such as easy aggregation of metal single atoms, low dispersion, unstable loading, and the extensive use of organic solvents in the preparation process, resulting in low preparation efficiency and resource utilization. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, this invention provides a metal atom catalyst and its synthesis method based on in-situ synthesis by ionization irradiation, thereby solving the problems of easy aggregation, low dispersion, and unstable loading of metal single atoms during the reduction process in the existing methods.

[0007] The specific details of the invention are as follows:

[0008] In a first aspect, the present invention provides a method for in-situ synthesis of metal atom catalysts based on ionizing radiation, the method comprising the following steps:

[0009] S1. Add the catalyst support and metal salt to an ethanol solution, stir at 50℃~70℃ for 1~4 h, and then filter out the solid. The mass ratio of metal ions in the catalyst support and metal salt is 100:9-30.

[0010] S2. The solid is vacuum dried, and then mixed with an appropriate amount of isopropanol and deionized water in a centrifuge tube. After the air in the centrifuge tube is removed, it is irradiated. The irradiation dose rate is 0.4~1.0 kGy / h, and the irradiation time is 6~25 h.

[0011] S3. The irradiated mixture is filtered, and the resulting solid is washed and vacuum dried to finally obtain the metal atom catalyst.

[0012] The catalyst support is a nitrogen-doped carbon material;

[0013] The composition of the metal salt includes soluble salts containing iron, cobalt, nickel, manganese or copper, or at least two of soluble salts containing iron, cobalt, nickel, manganese and copper mixed in any proportion.

[0014] Optionally, the mass-to-volume ratio of the catalyst support to the ethanol solution is 100 mg: 50-70 mL;

[0015] The mass-to-volume ratio of the catalyst support to the isopropanol is 100 mg: 1.5-2.0 μL.

[0016] Optionally, the vacuum drying process is carried out at a temperature of 40-60 °C for 6-12 h.

[0017] Optionally, the radiation source for the irradiation treatment is an electron accelerator, 60Co or 137 Cs.

[0018] Optionally, the temperature controlled by the constant temperature stirring is 60°C.

[0019] Optionally, the washing includes washing the obtained solid with deionized water 1-5 times.

[0020] Optionally, the catalyst support is graphitic carbon nitride, and the metal salt is at least one of CuCl2, FeCl3·6H2O, and CoCl2·6H2O.

[0021] Optionally, the irradiation dose rate is 0.5~18 kGy / h, and the irradiation time is 8~10 h.

[0022] Optionally, the process of purging the air from the centrifuge tube includes: introducing nitrogen gas into the centrifuge tube for 15-30 seconds to purge the air from the centrifuge tube.

[0023] In a second aspect, the present invention provides a metal atom catalyst obtained by the method of in-situ synthesis of metal atom catalysts based on ionization irradiation as described in the first aspect above.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] This invention provides a method for in-situ synthesis of metal atom catalysts based on ionizing radiation. The method includes the following steps: S1, adding a catalyst support and a metal salt to an ethanol solution, stirring at 50℃~70℃ for 1~4 h, and then filtering out the solid; S2, vacuum drying the solid, then mixing it with an appropriate amount of isopropanol in a centrifuge tube, removing the air from the centrifuge tube, and then irradiating it at an irradiation dose rate of 0.4~1.0 kGy / h for 6~25 h; S3, filtering the irradiated mixture, washing and vacuum drying the obtained solid to finally obtain the metal atom catalyst; wherein, the catalyst support is carbon nitride, inorganic molecular sieve, porous alumina, or porous carbon; the metal salt includes one of the soluble salts of iron, cobalt, nickel, manganese, and copper, or a mixture of multiple salts in any proportion.

[0026] In the synthesis method provided by this invention, ethanol is directly used as the solvent when mixing the catalyst support and the metal salt. Ethanol not only promotes the dissolution of the metal salt but also provides a uniform dispersion environment for the catalyst support material, ensuring sufficient dissolution and dispersion of the catalyst support and the metal salt, thus preventing the aggregation of metal ions during the subsequent irradiation reduction process. Furthermore, this invention mixes the irradiated material with isopropanol and then irradiates the isopropanol-containing irradiation system. Isopropanol, as a reducing agent, helps reduce the metal salt to metal atoms. Since metal atoms tend to aggregate during formation, this invention utilizes isopropanol to provide steric hindrance for the reduction of metal atoms on the catalyst support, thereby reducing the tendency for metal atom aggregation and promoting the formation of the metal atom catalyst. More importantly, the presence of isopropanol allows the metal salt to gain a certain degree of fluidity during irradiation, which helps increase the loading of metal atoms on the catalyst support. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 A flowchart of a method for in-situ synthesis of metal atom catalysts based on ionization irradiation, provided in an embodiment of the present invention, is shown.

[0029] Figure 2 The image shown is a spherical aberration electron microscope image of the in-situ synthesis of metal atom catalysts based on ionization irradiation provided in Example 1 of the present invention;

[0030] Figure 3 The image shown is a spherical aberration electron microscope image of the in-situ synthesis of metal atom catalysts based on ionization irradiation provided in Example 2 of the present invention;

[0031] Figure 4 The image shown is a spherical aberration electron microscope image of the in-situ synthesis of metal atom catalysts based on ionization irradiation provided in Example 3 of the present invention;

[0032] Figure 5 A spherical aberration electron microscope image of the in-situ synthesis of metal atom catalysts based on ionization irradiation provided in Example 4 of the present invention is shown. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention. Furthermore, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of the present invention.

[0034] Specific experimental steps or conditions are not specified in the embodiments; they can be performed according to the conventional experimental steps or conditions described in the prior art. Reagents and other instruments used, unless otherwise specified, are all commercially available conventional reagent products. Furthermore, the accompanying drawings are merely illustrative diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore, repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0035] Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of this specification.

[0036] In the description of this invention, it should be understood that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0037] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0038] Before providing a detailed description of the metal atom catalyst and its synthesis method based on in-situ synthesis under ionizing radiation provided by this invention, it is necessary to explain the relevant technologies as follows:

[0039] Patent (CN 112691689 B) discloses a method for the vapor irradiation reduction synthesis of a metal atom catalyst. In this invention, a catalyst support and a noble metal catalyst are first dispersed in an aqueous solution by stirring, and the pH of the solution is adjusted to 10. The resulting solution is then freeze-dried, and the freeze-dried solid is subjected to ethanol vapor in an ethanol vapor environment. The catalyst is then irradiated with a gamma radiation source under an inert atmosphere at a dose of 100 kGy, ultimately yielding a highly dispersed metal atom catalyst. While this patent ultimately synthesizes a highly dispersed metal atom catalyst, the pretreatment process before irradiation is complex, requiring the mixing of the catalyst support and the noble metal catalyst in an alkaline environment. The irradiation process also requires an inert gas environment, and the required irradiation dose is relatively high, resulting in high costs.

[0040] Patent (CN 108906113 A) discloses a method for synthesizing high-load noble metal atom catalysts using ultraviolet irradiation. In this invention, nitrogen-doped carbon materials are first mixed with a quantitative amount of noble metal acid or salt, allowing for sufficient adsorption of metal ions. After drying, the mixture is then irradiated with ultraviolet light to obtain the noble metal atom catalyst. While this method yields noble metal atom catalysts, the loading is only between 0.13 wt.% and 9.8 wt.%, and the noble metal is prone to agglomeration during the preparation process, resulting in uneven dispersion of metal single atoms.

[0041] Based on this, the present invention proposes a metal atom catalyst synthesized in situ by ionizing radiation and a synthesis method thereof. This process is simple, low-cost, and significantly reduces the required irradiation dose. The prepared metal atom catalyst exhibits high dispersion and loading of single metal atoms, providing an economical, efficient, and scalable method for the synthesis of carbon-supported multi-metal atom catalysts. Specific implementation details are as follows:

[0042] In a first aspect, the present invention provides a method for in-situ synthesis of metal atom catalysts based on ionizing radiation, the method comprising the following steps:

[0043] S1. Add the catalyst support and metal salt to the ethanol solution, stir at 50℃~70℃ for 1~4 h, and then filter out the solid.

[0044] In this step, when mixing the catalyst support and metal salt, ethanol is used directly as the solvent. Ethanol not only promotes the dissolution of the metal salt but also provides a uniform dispersion environment for the catalyst support material. Stirring at a constant temperature of 50℃~70℃ for 1~4 hours further aids in the dissolution of the metal salt and the dispersion of the catalyst support material, thereby promoting the uniform distribution of metal atoms in the catalyst. The preferred stirring temperature is 60℃.

[0045] In specific implementations, the catalyst support may be selected from nitrogen-doped carbon materials; the composition of the metal salt includes soluble salts containing iron, cobalt, nickel, manganese, or copper, or at least two of the soluble salts containing iron, cobalt, nickel, manganese, and copper mixed in any proportion. As a preferred example, the catalyst support may be graphitic carbon nitride, and the metal salt is selected from at least one of CuCl2, FeCl3·6H2O, and CoCl2·6H2O.

[0046] It should be noted that in the process of adding the catalyst support and metal salt to the ethanol solution, the mass ratio of metal ions in the selected catalyst support and metal salt should be controlled at 100:9-30; the amount of ethanol solution should be enough to submerge the catalyst support and metal salt. As an example, the mass-volume ratio of catalyst support to ethanol solution can be controlled at 100 mg:50-70 mL.

[0047] S2. The solid is vacuum dried, and then mixed with an appropriate amount of isopropanol and deionized water in a centrifuge tube. After the air in the centrifuge tube is removed, it is irradiated. The irradiation dose rate is 0.4~1.0 kGy / h, and the irradiation time is 6~25 h.

[0048] After step S1, the catalyst support and metal salt are fully dissolved and dispersed in an ethanol solution. The resulting solid material is formed by the catalyst support and the metal salt infiltrated into the surface and pores of the support. The resulting solid material is then vacuum dried to remove ethanol and excess moisture at a temperature of 40–60 °C for 6–12 h. Next, an appropriate amount of isopropanol solution is added to the vacuum-dried solid material, followed by irradiation. Isopropanol primarily acts as a quencher for hydroxyl radicals generated in the irradiation system, creating a system dominated by reducing active particles. Furthermore, the alcohol radicals formed after propanol quenches hydroxyl radicals also possess reducing properties. Under the combined action of the reducing active species (primary) and alcohol radicals (secondary) in the irradiation system, the metal salt is reduced to metal atoms. Furthermore, since metal atoms tend to aggregate during the formation process, the nitrogen sites in the graphitic carbon nitride used in this invention can capture metal atoms and reduce them in situ to metal single atoms, thereby reducing the tendency of metal atoms to aggregate and promoting the formation of metal atom catalysts.

[0049] In practice, this step involves irradiating the centrifuge tube after purging the air from the tube. Specifically, nitrogen gas can be introduced into the centrifuge tube for 15-30 seconds to purge the air. This step does not require an inert atmosphere for irradiation; the radiation source can be an electron accelerator. 60 Co or 137Cs; and since the irradiated object exists in a liquid environment, the selected irradiation treatment has an irradiation dose rate of 0.4~1.0 kGy / h and an irradiation time of 6~25 h, resulting in a significantly reduced total irradiation dose, ranging from 2.4 to 25 kGy. As a preferred example, the irradiation dose rate can be controlled at 0.5~0.8 kGy / h and the irradiation time at 8~10 h.

[0050] S3. The irradiated mixture is filtered, and the resulting solid is washed and vacuum dried to finally obtain the metal atom catalyst.

[0051] This step is used to separate and purify the metal atom catalyst generated in the irradiation system. The separation method is vacuum filtration to remove the isopropanol solution in the irradiation system. The obtained solid is washed and vacuum dried to finally obtain the metal atom catalyst. The washing operation specifically includes washing the obtained solid with deionized water 1-5 times.

[0052] In a second aspect, the present invention provides a metal atom catalyst obtained by the method of in-situ synthesis of metal atom catalysts based on ionization irradiation as described in the first aspect above.

[0053] To enable those skilled in the art to more clearly understand the present invention, the following embodiments will be used to provide a detailed description of a metal atom catalyst and its synthesis method based on in-situ synthesis by ionization irradiation.

[0054] It should be noted that the isopropanol reagent used in the embodiments of the present invention is a commercially available product with a purity of 99.9%.

[0055] Example 1

[0056] 100 mg of graphitic carbon nitride and 80.6 mg of CoCl2·6H2O (the mass of cobalt ions is approximately 19.96 mg) were added to 50 ml of ethanol solution (in a capped glass bottle) and kept at a constant temperature of 60°C. o Stir for 2 hours, then vacuum dry (60°C). o C). The resulting solid was then transferred to a 15 ml centrifuge tube, and 1.7 μL of isopropanol and deionized water (isopropanol concentration: 0.1 M) were added. The tube was capped. Irradiation was carried out at a dose rate of 0.6 kGy / h for 8 hours, followed by 1 h of incubation. The solid was then vacuum filtered, washed with deionized water (100 ml of deionized water stirred for 1 h), filtered again, and vacuum dried (60 °C). o C) This yields a carbon nitride-supported cobalt metal atom catalyst.

[0057] Figure 2The image shows aberration-corrected electron micrograph of the metal atom catalyst provided in Example 1 of the present invention. The left image shows the overall structure of the material, and the right image shows the distribution of cobalt metal atoms within the material. Figure 2 As shown, cobalt metal atoms are uniformly distributed in the metal atom catalyst and there are a large number of them. According to ICP-MS analysis, the loading rate of single cobalt atoms in the metal atom catalyst prepared in Example 1 reached 17.4%.

[0058] Example 2

[0059] 100 mg of graphitic carbon nitride and 20 mg of CuCl2 (approximately 9.44 mg of copper ions) were added to 50 ml of ethanol solution (in a capped glass bottle) and kept at a constant temperature of 60°C. o Stir for 2 hours, then vacuum dry (60°C). o C). The resulting solid was then transferred to a 15 ml centrifuge tube, and 1.7 μL of isopropanol and deionized water (isopropanol concentration: 0.1 M) were added. The tube was capped. Irradiation was carried out at a dose rate of 0.6 kGy / h for 8 hours, followed by 1 h of incubation. The solid was then vacuum filtered, washed with deionized water (100 ml of deionized water stirred for 1 h), filtered again, and vacuum dried (60 °C). o C) This yields a carbon nitride-supported copper metal atom catalyst.

[0060] Figure 3 Aberration-corrected electron micrograph of the metal atom catalyst provided in Example 2 of the present invention is shown, as follows: Figure 3 As shown, copper metal atoms are uniformly distributed in the metal atom catalyst, and there are a large number of them.

[0061] Example 3

[0062] 100 mg of graphitic carbon nitride, 41.9 mg of FeCl3·6H2O (approximately 8.43 mg of iron ions), and 20 mg of CuCl2 (approximately 9.44 mg of copper ions) were added to 50 ml of ethanol solution (in a capped glass bottle) and kept at a constant temperature of 60°C. o Stir for 2 hours, then vacuum dry (60°C). o C). The resulting solid was then transferred to a 15 ml centrifuge tube, and 1.7 μL of isopropanol and deionized water (isopropanol concentration: 0.1 M) were added. The tube was capped. Irradiation was carried out at a dose rate of 0.6 kGy / h for 8 h. After standing for 1 h, the tube was vacuum filtered. The collected solid was washed with deionized water (100 ml of deionized water stirred for 1 h), then filtered under vacuum and dried (60 °C). o C) This yields a carbon nitride-supported copper and iron bimetallic atom catalyst.

[0063] Figure 4Aberration-corrected electron micrograph of the metal atom catalyst provided in Example 3 of the present invention is shown, as follows: Figure 4 As shown, copper and iron atoms are evenly distributed in the metal atom catalyst, and their numbers are relatively large.

[0064] Example 4

[0065] 100 mg of graphitic carbon nitride, 40.3 mg of CoCl2·6H2O (cobalt ions: approximately 10.01 mg), 41.9 mg of FeCl3·6H2O (iron ions: approximately 8.43 mg), and 20 mg of CuCl2 (copper ions: approximately 9.44 mg) were added to 50 ml of ethanol solution (in a capped glass bottle) and kept at a constant temperature of 60°C. o Stir at C for 2 h, then vacuum dry (60) o C). The resulting solid was then transferred to a 15 ml centrifuge tube, 1.7 μL of isopropanol and deionized water (isopropanol concentration 0.1 M) were added, and the tube was capped. Irradiation was carried out at a dose rate of 0.6 kGy / h for 8 h, followed by 1 h of standing. The mixture was then vacuum filtered, and the collected solid was washed with deionized water (100 ml of deionized water stirred for 1 h), then filtered again, and vacuum dried to obtain the carbon nitride-supported iron, cobalt, and copper trimetallic atom catalyst.

[0066] Figure 5 Aberration-corrected electron micrograph of the metal atom catalyst provided in Example 4 of the present invention is shown, as follows: Figure 5 As shown, iron, cobalt, and copper atoms are evenly distributed in the metal atom catalyst, and their numbers are relatively large.

[0067] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0068] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0069] The foregoing has provided a detailed description of a metal atom catalyst and its synthesis method based on in-situ synthesis by ionization irradiation provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for in-situ synthesis of metal atom catalysts based on ionizing radiation, characterized in that, The method includes the following steps: S1. Add the catalyst support and metal salt to an ethanol solution, stir at 50℃~70℃ for 1~4 h, and then filter out the solid. The mass ratio of metal ions in the catalyst support and metal salt is 100:9-30. S2. The solid is vacuum dried, and then mixed with an appropriate amount of isopropanol and deionized water in a centrifuge tube. After the air in the centrifuge tube is removed, it is irradiated. The irradiation dose rate is 0.4~1.0 kGy / h, and the irradiation time is 6~25h. S3. The irradiated mixture is filtered, and the resulting solid is washed and vacuum dried to finally obtain the metal atom catalyst. The catalyst support is a nitrogen-doped carbon material; The composition of the metal salt includes soluble salts containing iron, cobalt, nickel, manganese or copper, or at least two of the soluble salts containing iron, cobalt, nickel, manganese and copper mixed in any proportion. The mass-to-volume ratio of the catalyst support to the isopropanol is 100 mg: 1.5-2.0 μL; The radiation source for the irradiation treatment is an electron accelerator. 60 Co or 137 Cs.

2. The method for in-situ synthesis of metal atom catalysts based on ionizing radiation according to claim 1, characterized in that, The mass-to-volume ratio of the catalyst support to the ethanol solution is 100 mg: 50-70 mL.

3. The method for in-situ synthesis of metal atom catalysts based on ionizing radiation according to claim 1, characterized in that, The vacuum drying process is carried out at a temperature of 40~60 ℃ for 6~12 h.

4. The method for in-situ synthesis of metal atom catalysts based on ionizing radiation according to claim 1, characterized in that, In step S1, the temperature controlled by stirring is 60°C.

5. The method for in-situ synthesis of metal atom catalysts based on ionizing radiation according to claim 1, characterized in that, The washing process includes washing the obtained solid with deionized water 1-5 times.

6. The method for in-situ synthesis of metal atom catalysts based on ionizing radiation according to claim 1, characterized in that, The catalyst support is graphitic carbon nitride, and the metal salt is at least one of CuCl2, FeCl3•6H2O and CoCl2•6H2O.

7. The method for in-situ synthesis of metal atom catalysts based on ionizing radiation according to claim 1, characterized in that, The irradiation dose rate is 0.5~18 kGy / h, and the irradiation time is 8~10 h.

8. The method for in-situ synthesis of metal atom catalysts based on ionizing radiation according to claim 1, characterized in that, The process of purging air from the centrifuge tube includes: introducing nitrogen gas into the centrifuge tube for 15-30 seconds to purge the air from the centrifuge tube.

9. A metal atom catalyst obtained by the method of in-situ synthesis of metal atom catalyst based on ionizing radiation as described in any one of claims 1-8.

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