A method for preparing a carbon-based metal single-atom catalyst and its application

Abstract

The invention discloses a preparation method and application of a carbon-based metal single-atom catalyst. The preparation method comprises the following steps: S1: weighing a metal inorganic salt and a chelating agent according to a certain proportion, stirring and dissolving them in deionized water, and then putting them into an oven for drying to remove the solvent to form a dry gel; S2: pouring the dry gel into a ceramic crucible and putting it into a quartz tube furnace filled with inert gas to heat it to fully carbonize it, and obtaining a black foam material after cooling; S3: taking out the cooled black foam material and grinding it to obtain a target carbon-based metal single-atom catalyst material; the carbon-based metal single-atom catalyst of the invention has good metal atom dispersion, and has the advantages of being simple and convenient, low in manufacturing cost, fluffy in structure, high in electrical conductivity, good in electrocatalytic activity and easy in large-scale preparation.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon-based metal single-atom catalysts, and in particular to a preparation method of a carbon-based metal single-atom catalyst and application thereof. Background Art

[0002] In recent years, carbon-based metal single-atom catalysts have attracted widespread attention as an emerging catalytic material. This type of catalyst has the advantages of maximized atomic utilization, independent active sites, and catalytic properties different from traditional catalysts. Carbon-based metal single-atom catalysts achieve atomic-level catalytic site dispersion by dispersing single metal atoms on carbon carriers, thereby maximizing atomic utilization. This structure not only provides highly isolated active centers, avoiding the interaction between atoms in traditional nanoparticles, but also combines the advantages of high activity of homogeneous catalysts and stability and easy separation of heterogeneous catalysts.

[0003] At present, researchers at home and abroad have developed various types of metal single atom catalysts, which are mainly used in electrocatalysis, photocatalysis, environmental monitoring and energy conversion. Among them, carbon-based metal single atom catalysts play a vital role in the production of hydrogen by water electrolysis. This process requires highly active, low-cost and stable electrocatalysts, and carbon-based metal single atom catalysts just meet these requirements.

[0004] For example, single-atom iron catalysts prepared on porous carbon supports exhibit excellent water electrolysis activity and stability. The synthesized hollow carbon sphere-supported single-atom metal cobalt catalyst has a specific electronic structure, which gives it a weak Cl - adsorption capacity, thus showing excellent catalytic activity, selectivity and Cl resistance - Corrosive. Platinum is one of the traditional water electrolysis catalysts, but it is expensive and has limited stability. By dispersing platinum on a carrier in the form of single atoms, the catalyst cost can be significantly reduced and the stability can be improved, which is conducive to its widespread application in the water electrolysis hydrogen production industry.

[0005] In addition, the design and synthesis strategies of carbon-based metal single atom catalysts are crucial for their application in hydrogen electrochemical cycles. Researchers have developed a variety of methods to prepare and characterize such materials to optimize their performance in the process of hydrogen production by water electrolysis, which provides new possibilities for the development of green energy.

[0006] At present, researchers have developed a variety of methods for preparing single-atom catalysts, including coprecipitation, atomic layer deposition, hydrothermal synthesis, electrostatic adsorption, step-by-step reduction, impregnation, vapor deposition, sol-gel, carbon material-assisted, etc. However, most of the methods are still in the laboratory stage, and the preparation methods have certain limitations in controlling synthesis conditions, equipment requirements, and raw material acquisition, resulting in the existence of uneven bonding between metal ions and carriers, agglomeration and abnormal growth of catalysts, destruction of the structure of the carrier or sintering of the catalyst, inability to accurately control the dispersion of metal ions and the bonding mode of the carrier, high preparation cost, long preparation cycle, and unstable structure in the prepared single-atom catalysts, which seriously limit their practical applications. Therefore, it is imperative to develop a simple, efficient, and universal preparation method for carbon-based metal single-atom catalysts. Summary of the invention

[0007] In order to overcome the shortcomings of existing preparation technology, one of the purposes of the present invention is to provide a method for preparing a carbon-based metal single-atom catalyst to solve the above-mentioned traditional technical problems. The method has the advantages of simple preparation, low price and excellent electrocatalytic performance.

[0008] The second object of the present invention is to provide a carbon-based metal single-atom catalyst prepared by the above-mentioned preparation method of the carbon-based metal single-atom catalyst for application in hydrogen evolution catalytic reactions in new energy fields such as water electrolysis to produce hydrogen.

[0009] One of the purposes of the present invention is achieved by the following technical solution: A method for preparing a carbon-based metal single-atom catalyst comprises the following steps: S1: weighing a metal inorganic salt and a chelating agent in a certain proportion, stirring and dissolving them in deionized water, and then drying them in an oven to remove the solvent to form a dry gel; S2: pouring the dry gel into a ceramic crucible and placing it in a quartz tube furnace filled with inert gas to heat it to fully carbonize it, and obtaining a black foamy material after cooling; S3: The cooled black foamy material is taken out and ground to obtain the target carbon-based metal single atom catalyst material.

[0010] In a preferred embodiment of the method for preparing the carbon-based metal single-atom catalyst, the molar ratio of the metal inorganic salt to the chelating agent is 1:2-1:12.

[0011] In a preferred embodiment of the method for preparing the carbon-based metal single-atom catalyst, the metal in the metal inorganic salt is one of iron, cobalt, nickel, ruthenium, iridium and platinum.

[0012] In a preferred embodiment of the method for preparing the carbon-based metal single-atom catalyst, the chelating agent is one or more of ammonium citrate, diammonium EDTA, ammonium oxalate, ammonium tartrate, ammonium pentate or nitrilotriacetate.

[0013] As a preferred embodiment of the method for preparing the carbon-based metal single-atom catalyst, in step S1, the oven drying temperature is 100-200° C., and the drying time is 1-6 hours.

[0014] As a preferred embodiment of the method for preparing the carbon-based metal single atom catalyst, in step S2, the carbonization temperature is 400-650° C. and the carbonization time is 1-6 h.

[0015] The second object of the present invention is achieved by adopting the following technical solution: A carbon-based metal single-atom catalyst prepared by the method for preparing a carbon-based metal single-atom catalyst described in any one of the above items is used in hydrogen production by electrolysis of water.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The carbon-based metal single-atom catalyst of the present invention has good metal atom dispersion, and has the advantages of simplicity, low raw material and manufacturing costs, fluffy structure, high electrical conductivity, good electrocatalytic activity and easy large-scale preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 HRTEM photos of the carbon-based metal single-atom catalyst materials prepared in Examples 1-6: a. iron; b. cobalt; c. nickel; d. ruthenium; e. iridium; f. platinum.

[0018] Figure 2 The electrocatalytic hydrogen evolution performance of the carbon-based metal single-atom catalyst materials prepared in Examples 1-6. DETAILED DESCRIPTION

[0019] Below, in conjunction with specific embodiments, the present invention is further described. It should be noted that, under the premise of not conflicting, the embodiments described below or the technical features can be arbitrarily combined to form new embodiments. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0020] Unless otherwise specified, the reagents used in the examples can be purchased from the market.

[0021] Example 1 Weigh ferric nitrate and ammonium citrate into a glass beaker, where the molar ratio of ferric nitrate to ammonium citrate is 1:2, add deionized water and stir to dissolve. Transfer the above solution to an oven and dry it at 100°C for 6 hours to obtain a dry gel. Pour the above dry gel into a ceramic crucible and place it in an argon-filled tubular furnace and heat it to carbonize at 400°C for 6 hours. Finally, take out the cooled black foamy material and grind it to obtain a carbon-based metallic iron single-atom catalyst material. The microscopic morphology is as follows Figure 1 As shown in a. It can be seen from the figure that the iron atoms in the catalyst material are anchored in the carbon matrix in the form of independent individuals, with good single atom dispersion, no aggregation, and structural stability.

[0022] Example 2 Weigh cobalt nitrate and diammonium EDTA into a glass beaker, where the molar ratio of cobalt nitrate to diammonium EDTA is 1:4, add deionized water and stir to dissolve. Transfer the above solution to an oven and dry it at 120°C for 5 hours to obtain a dry gel. Pour the above dry gel into a ceramic crucible and place it in an argon-filled tubular furnace and heat it to carbonize at 450°C for 5 hours. Finally, take out the cooled black foamy material and grind it to obtain a carbon-based metal cobalt single-atom catalyst material. The microscopic morphology is as follows Figure 1 As shown in b. As can be seen from the figure, the cobalt atoms in the catalyst material are anchored in the carbon matrix in the form of independent individuals, with good single-atom dispersion, no aggregation, and structural stability.

[0023] Example 3 Weigh nickel nitrate and ammonium oxalate into a glass beaker, where the molar ratio of nickel nitrate to ammonium oxalate is 1:6, add deionized water and stir to dissolve. Transfer the above solution to an oven and dry it at 140°C for 4 hours to obtain a dry gel. Pour the above dry gel into a ceramic crucible and place it in an argon-filled tubular furnace and heat it to carbonize at 500°C for 4 hours. Finally, take out the cooled black foamy material and grind it to obtain a carbon-based metal nickel single-atom catalyst material. The microscopic morphology is as follows Figure 1 As shown in c. As can be seen from the figure, the nickel atoms in the catalyst material are anchored in the carbon matrix in the form of independent individuals, with good single-atom dispersion, no aggregation, and structural stability.

[0024] Example 4 Weigh ruthenium trichloride and ammonium tartrate into a glass beaker, where the molar ratio of ruthenium trichloride to ammonium tartrate is 1:8, add deionized water and stir to dissolve. Transfer the above solution to an oven and dry it at 160°C for 3 hours to obtain a dry gel. Pour the above dry gel into a ceramic crucible and place it in an argon-filled tubular furnace and heat it to carbonize it at 550°C for 3 hours. Finally, take out the cooled black foamy material and grind it to obtain a carbon-based metal ruthenium single-atom catalyst material. The microscopic morphology is as follows Figure 1 As shown in d. As can be seen from the figure, the ruthenium single atoms in the catalyst material are anchored in the carbon matrix in the form of independent individuals, with good single atom dispersion, no aggregation, and structural stability.

[0025] Example 5 Weigh iridium trichloride and ammonium pentate into a glass beaker, where the molar ratio of iridium trichloride to ammonium pentate is 1:10, add deionized water and stir to dissolve. Transfer the above solution to an oven and dry it at 180°C for 2 h to obtain a dry gel. Pour the above dry gel into a ceramic crucible and place it in an argon-filled tubular furnace and heat it to carbonize it at 600°C for 2 h. Finally, take out the cooled black foam material and grind it to obtain a carbon-based metal iridium single atom catalyst material. The microscopic morphology is as follows Figure 1 As shown in e. As can be seen from the figure, the iridium single atoms in the catalyst material are anchored in the carbon matrix in the form of independent individuals, the single atoms have good dispersion, no aggregation, and have the characteristics of structural stability.

[0026] Example 6 Weigh chloroplatinic acid and ammonium nitrilotriacetate into a glass beaker, where the molar ratio of chloroplatinic acid to ammonium nitrilotriacetate is 1:12, add deionized water and stir to dissolve. Transfer the above solution to an oven and dry it at 200°C for 1 h to obtain a dry gel. Pour the above dry gel into a ceramic crucible and place it in an argon-filled tubular furnace and heat it to carbonize it at 650°C for 1 h. Finally, take out the cooled black foamy material and grind it to obtain a carbon-based metal platinum single atom catalyst material. The microscopic morphology is as follows Figure 1 As shown in Figure f, it can be seen that the platinum atoms in the catalyst material are anchored in the carbon matrix in the form of independent individuals, with good single-atom dispersion, no aggregation, and structural stability.

[0027] Performance Test: 1. Electrocatalytic hydrogen evolution performance test The electrocatalytic hydrogen evolution performance of the carbon-based metal single atom catalysts of Examples 1-6 in 1 M KOH electrolyte was tested. The test results are as follows: Figure 2 shown.

[0028] Depend on Figure 2 It can be seen that the best performance among the six examples is the noble metal single atom catalyst system represented by platinum, iridium and ruthenium (Examples 4-6), followed by the non-noble metal single atom catalyst system represented by nickel, cobalt and iron (Examples 1-3). In addition, the three noble metal single atom catalysts show excellent electrocatalytic hydrogen evolution activity, which is only slightly different from the commercial noble metal material Pt / C. Considering the cost of use and electrocatalytic performance, the catalysts in Examples 4-6 have certain advantages.

[0029] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A method for preparing a carbon-based metal single-atom catalyst, characterized in that: The following steps are involved: S1: weighing a metal inorganic salt and a chelating agent in a certain proportion, stirring and dissolving them in deionized water, and then drying them in an oven to remove the solvent to form a dry gel; S2: pouring the dry gel into a ceramic crucible and placing it in a quartz tube furnace filled with inert gas to heat it to fully carbonize it, and obtaining a black foamy material after cooling; S3: The cooled black foamy material is taken out and ground to obtain the target carbon-based metal single atom catalyst material.

2. The method for preparing a carbon-based metal single-atom catalyst according to claim 1, characterized in that: The molar ratio of the metal inorganic salt to the chelating agent is 1:2-1:

12.

3. The method for preparing the carbon-based metal single-atom catalyst according to claim 1, characterized in that: The metal in the metal inorganic salt is one of iron, cobalt, nickel, ruthenium, iridium and platinum.

4. The method for preparing a carbon-based metal single-atom catalyst according to claim 1, characterized in that: The chelating agent is one or more of ammonium citrate, diammonium EDTA, ammonium oxalate, ammonium tartrate, ammonium pentate or nitrilotriacetate.

5. The method for preparing the carbon-based metal single-atom catalyst according to claim 1, characterized in that: In step S1, the oven drying temperature is 100-200°C, and the drying time is 1-6 hours.

6. The method for preparing a carbon-based metal single-atom catalyst according to claim 1, characterized in that: In step S2, the carbonization temperature is 400-650°C, and the carbonization time is 1-6 hours.

7. A carbon-based metal single-atom catalyst prepared by the method for preparing a carbon-based metal single-atom catalyst as described in any one of claims 1 to 6 is used in hydrogen production by electrolysis of water.

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