Nitrogen and sulfur co-doped mesoporous carbon catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of electro-catalytic materials, and relates to a nitrogen-sulfur co-doped mesoporous carbon catalyst and a preparation method and application thereof, the catalyst is a nitrogen-sulfur co-doped carbon-based material, and is obtained through self-assembly and high-temperature carbonization treatment by taking F127 as a template agent and taking m-aminothiophenol as a precursor. The catalyst has abundant active sites, an optimized electronic structure and mesoporous morphology, shows high activity, high selectivity and excellent stability in an electrocatalytic oxygen reduction reaction, and is suitable for an efficient and environment-friendly hydrogen peroxide electrosynthesis process.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic materials technology, and relates to a nitrogen-sulfur co-doped mesoporous carbon catalyst, its preparation method, and its application. Background Technology

[0002] Hydrogen peroxide is an important green oxidant and disinfectant with wide applications in chemical, environmental remediation, medical, and electronics industries. However, the main method for industrial production of hydrogen peroxide is currently the anthraquinone process, which requires complex processes, consumes large amounts of organic solvents, is energy-intensive, and causes some environmental pollution. With the rise of sustainable development and green chemistry concepts, developing more efficient and environmentally friendly methods for preparing hydrogen peroxide has become a research hotspot.

[0003] Electrocatalytic hydrogen peroxide production is a novel technology based on electrochemical principles. It can directly utilize water or oxygen as raw materials to generate hydrogen peroxide through an electrochemical reaction at ambient temperature and pressure. This technology has significant advantages such as simple process, low energy consumption, and no organic solvent pollution, and is considered a potential solution to replace the anthraquinone process.

[0004] Currently, electrocatalytic hydrogen peroxide production technology suffers from several drawbacks, limiting its widespread practical application. Most catalysts are complex and costly to prepare, restricting their large-scale application. The preparation processes are demanding, requiring specific pH or temperature ranges for operation, thus limiting their application scenarios. Furthermore, they suffer from insufficient electrochemical performance, such as high overpotentials and low current densities, resulting in low catalytic activity, leading to insufficient reaction rates and low yields, failing to meet the demands of high-efficiency production. Secondly, many catalysts exhibit poor selectivity, easily initiating side reactions and generating numerous byproducts, thereby reducing the purity of hydrogen peroxide. Thirdly, catalyst stability is a significant issue; during prolonged electrocatalytic processes, deactivation, corrosion, or structural collapse can easily occur, leading to a substantial reduction in lifespan. Summary of the Invention

[0005] To address the shortcomings of the prior art, this invention provides a nitrogen-sulfur co-doped mesoporous carbon catalyst, its preparation method, and its application. This catalyst exhibits high activity, high selectivity, and excellent stability. The preparation method of this invention is simple and efficient, which helps reduce production costs and is suitable for large-scale application. It provides an innovative solution for the efficient, economical, and stable electrosynthesis of hydrogen peroxide.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for preparing a nitrogen-sulfur co-doped mesoporous carbon catalyst includes the following steps: Using triblock copolymer F127 as a template agent, m-aminothiophenol as a precursor, and oil phase 1,3,5-trimethylbenzene in a solvent, spherical micelles with polyoxypropylene as the core and polyethylene oxide as the shell are formed. The oil phase 1,3,5-trimethylbenzene can swell the hydrophobic polyoxypropylene. Then, an initiator is added to initiate the oxidative polymerization reaction of m-aminothiophenol. After carbonization, a nitrogen-sulfur co-doped mesoporous carbon catalyst is obtained.

[0007] The solvent is a mixture of anhydrous ethanol and water.

[0008] The initiator is ammonium persulfate.

[0009] The solvent is a mixture of anhydrous ethanol and water.

[0010] The initiator is ammonium persulfate.

[0011] In a preferred embodiment of the present invention, the mass ratio of template agent F127, m-aminothiophenol and ammonium persulfate is 4~10:1~4:2~5.

[0012] In a preferred embodiment of the present invention, the volume ratio of 1,3,5-trimethylbenzene, anhydrous ethanol and water is 1~5:14~26:14~26.

[0013] In a preferred embodiment of the present invention, the rotation speed of the chemical oxidation polymerization reaction is 200 rpm to 800 rpm, the chemical oxidation polymerization reaction time is 12 h to 96 h, and the chemical oxidation polymerization reaction temperature is 10 °C to 30 °C.

[0014] In a preferred embodiment of the present invention, the post-treatment of the chemical oxidative polymerization reaction is centrifugal washing 1 to 5 times, and the washing liquid is ethanol and water, wherein the mass ratio of ethanol to water is 0 to 1:1.

[0015] In a preferred embodiment of the present invention, the carbonization is carried out in an inert atmosphere, the carbonization heating rate is 1℃ / min to 5℃ / min, and the carbonization temperature is 400℃ to 1000℃.

[0016] In a preferred embodiment of the present invention, the inert atmosphere is nitrogen or argon.

[0017] Another object of the present invention is a catalyst for nitrogen-sulfur co-doped mesoporous carbon obtained by any of the preparation methods described in any one of the inventions.

[0018] The application of the nitrogen-sulfur co-doped mesoporous carbon catalyst described in this invention in the electrocatalytic preparation of hydrogen peroxide.

[0019] The application of the nitrogen-sulfur co-doped mesoporous carbon catalyst of the present invention in the electrocatalytic preparation of hydrogen peroxide is characterized in that the catalyst is loaded on carbon paper as a working electrode, and hydrogen peroxide is prepared by electrocatalysis through a two-electron oxygen reduction reaction in an oxygen-saturated alkaline electrolyte using a flow electrolyzer.

[0020] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention uses triblock copolymer F127 as a template agent, dissolved in a solvent, to form spherical micelles with polypropylene oxide (PPO) as the core and polyethylene oxide (PEO) as the shell. The amino groups on m-aminothiophenol interact with PEO through hydrogen bonds. Adding 1,3,5-trimethylbenzeneylene to swell the hydrophobic PPO regions, followed by the addition of an initiator, initiates the oxidative polymerization of m-aminothiophenol. After carbonization, a nitrogen-sulfur co-doped mesoporous carbon catalyst is obtained. The solvent is a mixture of anhydrous ethanol and water; the initiator is ammonium persulfate. This invention is simple and efficient, helps reduce production costs, and is suitable for large-scale application.

[0021] 2. This invention effectively optimizes the distribution of active sites and electron transport characteristics by utilizing in-situ nitrogen-sulfur co-doping and tunable mesoporous structure and morphology, thereby significantly enhancing intrinsic catalytic activity and greatly improving the generation efficiency of hydrogen peroxide. Simultaneously, through precise control of the surface chemical properties of the material, side reactions are effectively suppressed, reaction selectivity is improved, and the high purity of the hydrogen peroxide product is ensured. Furthermore, the material possesses excellent structural stability and corrosion resistance, enabling long-term stable operation in harsh electrocatalytic environments while maintaining high catalytic activity and significantly extending its service life. More importantly, this catalyst exhibits broad environmental adaptability and effectively reduces reaction overpotential and increases reaction current density, thus overcoming the limitations of traditional catalysts in electrochemical performance and providing an innovative solution for the efficient, economical, and stable electrosynthesis of hydrogen peroxide. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Figure 1 This is a SEM image of the catalyst sample prepared in Example 1 of the present invention.

[0024] Figure 2 This is a TEM image of the catalyst sample prepared in Example 1 of the present invention.

[0025] Figure 3 The above is the XPS spectrum of the catalyst sample prepared in Example 1 of this invention.

[0026] Figure 4 The selectivity of the catalyst sample prepared in Example 1 of this invention for the electrocatalytic production of hydrogen peroxide.

[0027] Figure 5 The graph shows the yield and faradaic efficiency of the catalyst sample prepared in Example 1 of this invention for the electrocatalytic production of hydrogen peroxide. The bar graph represents the corresponding hydrogen peroxide yield obtained under different voltages, and the dotted line graph represents the corresponding faradaic efficiency obtained under different voltages.

[0028] Figure 6 This is a stability graph of the catalyst sample prepared in Example 1 of the present invention, where the bar graph represents the corresponding hydrogen peroxide yield obtained at different times; the broken line represents the corresponding Faraday efficiency obtained at different times; and the circle represents the corresponding voltage obtained at different times.

[0029] Figure 7 This is a SEM image of the catalyst sample prepared in Comparative Example 1 of this invention.

[0030] Figure 8 This is a SEM image of the catalyst sample prepared in Comparative Example 2 of this invention. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0032] The following detailed description, in conjunction with embodiments of the present invention and accompanying drawings, provides a clear and complete illustration of the technical solutions in these embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0033] It should be noted that all technical terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0034] Example 1 A method for preparing a nitrogen-sulfur co-doped mesoporous carbon catalyst includes the following steps: (1) Using 2g of F127 as a template agent, 500uL of m-aminothiophenol as a precursor, 3mL of 1,3,5-trimethylbenzene, 20mL of anhydrous ethanol and 20mL of water as solvents, and 2.5g of ammonium persulfate as an initiator, m-aminothiophenol underwent a chemical oxidative polymerization reaction at a reaction temperature of 20℃ and a reaction time of 24h to obtain a mixed solution. The solution was then centrifuged and washed 5 times. The washing liquid was ethanol and water with a mass ratio of 1:1 to obtain a solid powder.

[0035] (2) The solid powder is carbonized in an inert atmosphere of argon, the carbonization heating rate is 5℃ / min, and the carbonization temperature is 800℃ to obtain a nitrogen-sulfur co-doped mesoporous carbon catalyst.

[0036] Example 2 (1) Using 1.25 g of F127 as a template agent, 637 μL of m-aminothiophenol as a precursor, 1 mL of 1,3,5-trimethylbenzene, 14 mL of anhydrous ethanol and 14 mL of water as solvents, and 0.75 g of ammonium persulfate as an initiator, m-aminothiophenol underwent a chemical oxidative polymerization reaction at a reaction temperature of 30 °C for 60 h to obtain a mixed solution. The solution was then centrifuged and washed three times with ethanol and water as washing liquids in a mass ratio of 1:1 to obtain a solid powder.

[0037] (2) The solid powder is carbonized in an inert atmosphere of argon, the carbonization heating rate is 3℃ / min, and the carbonization temperature is 1000℃ to obtain a nitrogen-sulfur co-doped mesoporous carbon catalyst.

[0038] Example 3 (1) Using 2.5g of F127 as a template agent, 847uL of m-aminothiophenol as a precursor, 3mL of 1,3,5-trimethylbenzene, 20mL of anhydrous ethanol and 20mL of water as solvents, and 1.25g of ammonium persulfate as an initiator, m-aminothiophenol underwent a chemical oxidative polymerization reaction at a reaction temperature of 10℃ and a reaction time of 96h to obtain a mixed solution. The solution was then centrifuged and washed three times with ethanol and water as washing liquids in a mass ratio of 1:1 to obtain a solid powder.

[0039] (2) The solid powder is carbonized in an inert atmosphere of argon, the carbonization heating rate is 5℃ / min, and the carbonization temperature is 1000℃ to obtain a nitrogen-sulfur co-doped mesoporous carbon catalyst.

[0040] Example 4 (1) Using 2.1 g of F127 as a template agent, 806 μL of m-aminothiophenol as a precursor, 5 mL of 1,3,5-trimethylbenzene, 26 mL of anhydrous ethanol and 26 mL of water as solvents, and 1.1 g of ammonium persulfate as an initiator, m-aminothiophenol underwent a chemical oxidative polymerization reaction at a reaction temperature of 25 °C for 12 h to obtain a mixed solution. The solution was then centrifuged and washed once with ethanol and water in a mass ratio of 0:1 to obtain a solid powder.

[0041] (2) The solid powder is carbonized in an inert atmosphere of argon, the carbonization heating rate is 1℃ / min, and the carbonization temperature is 400℃ to obtain a nitrogen-sulfur co-doped mesoporous carbon catalyst.

[0042] Comparative Example 1 (1) Using 500 μL of m-aminothiophenol as a precursor, 200 mL of anhydrous ethanol and 200 mL of water as solvents, and 2.5 g of ammonium persulfate as an initiator, m-aminothiophenol undergoes a chemical oxidation polymerization reaction for 10 h to obtain a mixed solution. The solution is then centrifuged and washed once. The washing liquid is ethanol and water with a mass ratio of 1:1 to obtain a solid powder.

[0043] (2) The solid powder is carbonized in an inert atmosphere of argon, the carbonization heating rate is 5℃ / min, and the carbonization temperature is 1000℃ to obtain a nitrogen-sulfur co-doped mesoporous carbon catalyst.

[0044] Comparative Example 2 (1) Using 500 μL of m-aminothiophenol as a precursor, 10 mL of 1,3,5-trimethylbenzene, 200 mL of anhydrous ethanol and 200 mL of water as solvents, and 2 g of ammonium persulfate as an initiator, m-aminothiophenol undergoes a chemical oxidation polymerization reaction for 10 h to obtain a mixed solution. The solution is then centrifuged and washed three times with ethanol and water as washing liquids in a mass ratio of 1:1 to obtain a solid powder.

[0045] (2) The solid powder is carbonized in an inert atmosphere of argon, the carbonization heating rate is 1℃ / min, and the carbonization temperature is 400℃ to obtain a nitrogen-sulfur co-doped mesoporous carbon catalyst.

[0046] Results Analysis Figure 1 The image shows a SEM image of the catalyst sample prepared in Example 1 of this invention, which indicates the presence of a distinct mesoporous structure with a particle size of approximately 200 nm.

[0047] Figure 2 The image shows a TEM image of the catalyst sample prepared in Example 1 of this invention, indicating that there are obvious open structures and mesopores in the material framework.

[0048] Figure 3 The XPS spectrum of the catalyst sample prepared in Example 1 of this invention shows that four elements, C, N, O and S, are present in the material.

[0049] Figure 4 The figure shows the selectivity of the catalyst sample prepared in Example 1 of this invention for the electrocatalytic production of hydrogen peroxide. The selectivity of hydrogen peroxide is approximately 90%.

[0050] Figure 5 The figure shows the yield and Faraday efficiency of the catalyst sample prepared in Example 1 of this invention for the electrocatalytic production of hydrogen peroxide. The yield of hydrogen peroxide is 18 mol·g. -1 ·h -1 .

[0051] Figure 6 This is a stability graph of the catalyst sample prepared in Example 1 of the present invention. The graph shows that the catalyst in 0.1 M KOH solution has a stability of 200 mA·cm⁻¹. -2 Continuous electrolysis was performed for 50 hours. During this process, a stable voltage was observed, and the yield of H₂O₂ was 15.8 mol·g⁻¹. -1 ·h -1 The Faraday efficiency remained above 80%, indicating that the catalyst has good stability.

[0052] The performance of the other embodiments is similar to that of Embodiment 1, and will not be described in detail here.

[0053] Figure 7 The image shows a SEM image of the catalyst sample prepared in Comparative Example 1 of this invention. The image shows that the sample particles are uneven in size, severely agglomerated, and have an irregular morphology. Since there is no guiding effect of F127 as a template agent, the monomer m-aminothiophenol will polymerize arbitrarily, resulting in the polymer exhibiting a granular aggregated structure.

[0054] Figure 8 The image shows a SEM image of the catalyst sample prepared in Comparative Example 2 of this invention. The image shows that the sample exhibits large-area adhesion and lacks a specific morphology and pore structure.

[0055] Therefore, to form a regular morphology, both template agent F127 and oil phase 1,3,5-trimethylbenzene are required. There is a synergistic effect between the two, and the absence of either one will prevent the formation of a regular mesoporous carbon material.

[0056] This invention leverages in-situ nitrogen-sulfur co-doping and tunable mesoporous structure and morphology to effectively optimize the distribution of active sites and electron transport characteristics, thereby significantly enhancing intrinsic catalytic activity and greatly improving the generation efficiency of hydrogen peroxide. Simultaneously, through precise control of the material's surface chemical properties, side reactions are effectively suppressed, reaction selectivity is improved, and the high purity of the hydrogen peroxide product is ensured. Furthermore, the material possesses excellent structural stability and corrosion resistance, enabling long-term stable operation in harsh electrocatalytic environments while maintaining high catalytic activity and significantly extending its service life. More importantly, this catalyst exhibits broad environmental adaptability and effectively reduces reaction overpotential and increases reaction current density, thus overcoming the limitations of traditional catalysts in electrochemical performance and providing an innovative solution for the efficient, economical, and stable electrosynthesis of hydrogen peroxide.

[0057] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, it is intended to include any modifications and variations that fall within the scope of the claims and their equivalents.

Claims

1. A method for preparing a nitrogen-sulfur co-doped mesoporous carbon catalyst, characterized in that, Includes the following steps: Using triblock copolymer F127 as a template agent, m-aminothiophenol as a precursor, and oil phase 1,3,5-trimethylbenzene dissolved in a solvent, spherical micelles with polyoxypropylene as the core and polyethylene oxide as the shell are formed. The oil phase 1,3,5-trimethylbenzene is used to swell the hydrophobic polyoxypropylene. Then, an initiator is added to initiate the oxidative polymerization reaction of m-aminothiophenol. After carbonization, a nitrogen-sulfur co-doped mesoporous carbon catalyst is obtained. The solvent is a mixture of anhydrous ethanol and water; The initiator is ammonium persulfate.

2. The method for preparing the nitrogen-sulfur co-doped mesoporous carbon catalyst according to claim 1, characterized in that, The mass ratio of template agent F127, m-aminothiophenol and ammonium persulfate is 4~10:1~4:2~5.

3. The method for preparing the nitrogen-sulfur co-doped mesoporous carbon catalyst according to claim 1, characterized in that, The volume ratio of 1,3,5-trimethylbenzene, anhydrous ethanol, and water is 1~5:14~26:14~26.

4. The method for preparing the nitrogen-sulfur co-doped mesoporous carbon catalyst according to claim 1, characterized in that, The rotation speed of the chemical oxidative polymerization reaction is 200 rpm to 800 rpm, the reaction time is 12 h to 96 h, and the reaction temperature is 10 ℃ to 30 ℃.

5. The method for preparing the nitrogen-sulfur co-doped mesoporous carbon catalyst according to claim 1, characterized in that, The post-treatment of the chemical oxidative polymerization reaction is centrifugation and washing 1 to 5 times, with the washing solution being ethanol and water, and the mass ratio of ethanol to water being 0 to 1:

1.

6. The method for preparing the nitrogen-sulfur co-doped mesoporous carbon catalyst according to claim 1, characterized in that, The carbonization was carried out under a protective atmosphere, with a carbonization heating rate of 1℃ / min to 5℃ / min and a carbonization temperature of 400℃ to 1000℃.

7. The method for preparing the nitrogen-sulfur co-doped mesoporous carbon catalyst according to claim 6, characterized in that, The inert atmosphere is nitrogen or argon.

8. The nitrogen-sulfur co-doped mesoporous carbon catalyst obtained by the preparation method according to any one of claims 1 to 7.

9. The application of the nitrogen-sulfur co-doped mesoporous carbon catalyst according to claim 8 in the electrocatalytic preparation of hydrogen peroxide.

10. The application of the nitrogen-sulfur co-doped mesoporous carbon catalyst according to claim 9 in the electrocatalytic preparation of hydrogen peroxide, characterized in that, The catalyst was loaded onto carbon paper as the working electrode, and hydrogen peroxide was prepared by electrocatalysis via a two-electron oxygen reduction reaction in a flow electrolytic cell in an oxygen-saturated alkaline electrolyte.

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