Nitrogen-doped spherical mesoporous carbon material with dispersed metal atoms and preparation method thereof

Abstract

The application relates to the technical field of carbon material preparation, and discloses a nitrogen-doped spherical mesoporous carbon material dispersing metal single atoms and a preparation method thereof, which comprises the following steps: introducing a metal precursor containing a vinyl group in a prepolymer stage, and grafting a metal center on a polymer skeleton in situ through chemical bonding; then, using an amphiphilic block copolymer as a soft template, combining an emulsification solidification process to prepare a phenolic resin ball; finally, carbonizing the resin ball, and activating the resin ball by inputting water vapor with a specific proportion, so that mesopores and micropores are constructed. The application effectively inhibits the agglomeration of metal atoms at high temperatures through in-situ chemical bonding, and realizes the high-dispersion loading of single atoms; meanwhile, the synergistic effect of the soft template and water vapor activation endows the material with a high specific surface area and a developed hierarchical pore structure. When the obtained material is used as an electrode of a super capacitor, the material exhibits high specific capacitance, excellent rate performance and good cycle stability.

Description

Technical Field

[0001] This invention relates to the field of carbon material preparation technology, specifically to a nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms and its preparation method. Background Technology

[0002] Mesoporous carbon materials have potential applications in energy storage and conversion, catalysis, and adsorption due to their structural characteristics. In terms of morphology, spherical carbon materials exhibit higher packing density and structural stability compared to non-spherical materials, which is beneficial for accommodating more active substances within a limited space and ensuring the material's performance during long-term use. Phenolic resins are commonly used precursors for preparing these carbon materials due to their high char residue and good thermal stability. During the synthesis of phenolic resins, alkaline conditions are milder and more controllable than acidic conditions, which is conducive to forming a precursor with a uniform structure, resulting in a more developed pore structure in the subsequent carbonization material.

[0003] Currently, to further improve the performance of carbon materials, porosity control and functional modification are commonly employed. However, in terms of pore structure construction, existing technologies often use hard template methods such as silica to prepare porous structures. This method is cumbersome, requiring the use of strong alkalis or acids to etch and remove the template, which not only increases production costs and environmental impact, but also causes template residue to contaminate the pores, affecting the purity and performance of the material.

[0004] Direct impregnation is a common method for introducing metal active sites, which involves immersing the formed carbon material in a metal salt solution. However, this method makes it difficult to control the metal dispersion, and the metal particles are prone to migration and agglomeration during subsequent heat treatment, forming larger particles. This not only reduces the utilization rate of active sites but also blocks the material pores, affecting mass transport.

[0005] For nitrogen doping, some techniques employ methods such as calcination in an ammonia atmosphere after carbon material molding. This post-processing method often results in uneven distribution of nitrogen on the substrate, and the thermodynamic stability of the supported nitrogen species is poor, affecting the uniformity and long-term effectiveness of the overall electrochemical performance of the material. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms and a preparation method thereof. This solves the problem that existing technologies struggle to synergistically achieve high dispersion loading of metal atoms, uniform doping of nitrogen, and effective construction of hierarchical pore structures when preparing metal single-atom-doped carbon materials, resulting in insufficient electrochemical performance of the materials.

[0007] To address the above problems, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides a nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms, said carbon material being made from raw materials comprising the following parts by weight:

[0009] 45-55 parts of phenol;

[0010] 9-13 parts of aminophenol;

[0011] 100-120 parts of a 37% formaldehyde aqueous solution;

[0012] 0.4-0.6 parts of a vinyl-containing metallocene precursor;

[0013] 6-8 parts of triblock copolymer pore-forming agent;

[0014] 4.5-8.0 parts of hexamethylenetetramine.

[0015] By employing the above technical solution, this invention utilizes a specific ratio of phenol and aminophenol as carbon and nitrogen sources, introduces a vinyl-containing metallocene precursor, and, in conjunction with a block copolymer pore-forming agent, achieves high dispersion of metal single atoms within a nitrogen-doped carbon framework. Its mechanism of action is as follows:

[0016] Dual-source copolymerization introduces coordination sites: Phenol and aminophenol undergo a condensation reaction under the action of formaldehyde, and aminophenol introduces nitrogen atoms into the polymer backbone. These nitrogen atoms, acting as Lewis bases, donate electrons to provide coordination sites for metal atoms, forming a stable metal-nitrogen coordination structure.

[0017] In-situ chemical bonding of vinyl groups: Vinyl-containing metallocene precursors participate in the polymerization of phenolic resins using their vinyl functional groups. The metal precursor enters the polymer chain through covalent bonding. This chemical bonding restricts the migration of metal atoms during high-temperature carbonization, thereby inhibiting the aggregation of metal atoms and ensuring that the metal exists in the final product in a single-atom form.

[0018] Mesoporous spherical structure regulation: Triblock copolymers are used as soft templates to guide the assembly of precursors to form an ordered mesoporous structure. Hexamethylenetetramine is used as a curing agent and supplemented with nitrogen source to ensure the curing and shaping of the spherical structure, thereby obtaining a spherical mesoporous structure with a large specific surface area.

[0019] Preferably, the aminophenol is selected from one of p-aminophenol and m-aminophenol; the vinyl-containing metallocene precursor is selected from one of vinyl ferrocene and vinyl cobalt cadmium.

[0020] By adopting the above technical solution, the polymerization rate and crosslinking degree are adjusted by utilizing the isomer structure of aminophenol; and the thermal stability of metallocene derivatives is utilized to decompose and release metal atoms at high temperature, which are then captured by the surrounding nitrogen atoms.

[0021] Preferably, the triblock copolymer pore-forming agent is a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer; the raw material also includes a dispersant, which is a polyvinyl alcohol aqueous solution with a mass concentration of 1%-3%.

[0022] By adopting the above technical solution, the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer forms micelles through self-assembly, generating mesoporous channels inside the polymer; polyvinyl alcohol adjusts the oil-water interfacial tension and controls the droplet size, so that the product has a uniform spherical morphology.

[0023] Preferably, the mass ratio of phenol to aminophenol in the raw materials is 5:(1-1.2); and the mass ratio of the triblock copolymer pore-forming agent to phenol is 1:(7-9).

[0024] By adopting the above technical solutions, controlling the ratio of phenol to aminophenol can adjust the crosslinking density and nitrogen content of the polymer, avoiding structural collapse caused by excessive nitrogen content; and controlling the proportion of pore-forming agent can balance porosity and mechanical strength.

[0025] Preferably, the carbon material has a spherical morphology, and the metal single atoms are dispersed in the nitrogen-doped carbon framework by in-situ grafting.

[0026] Secondly, the present invention provides a method for preparing nitrogen-doped spherical mesoporous carbon materials with dispersed metal single atoms, comprising the following steps:

[0027] S1. Phenol and aminophenol are dissolved in an alkaline aqueous solution to obtain a phenolamine solution;

[0028] S2. Add formaldehyde aqueous solution dropwise to the solution obtained in step S1, and heat to carry out prepolymerization reaction to obtain prepolymer;

[0029] S3. Lower the temperature of the prepolymer, add an alcohol solution containing a vinyl metallocene precursor, and stir to allow the metal precursor and prepolymer to undergo a grafting reaction.

[0030] S4. Add a triblock copolymer pore-forming agent and dispersant solution to the reactants obtained in step S3, stir and emulsify, then add hexamethylenetetramine, heat and cure, and the product is post-treated to obtain phenolic resin balls.

[0031] S5. The phenolic resin balls are subjected to multi-stage heat treatment: first, oxidation is carried out in an air atmosphere; then, carbonization is carried out in an inert atmosphere; then, water vapor is introduced for activation under inert atmosphere protection, and the carbon material is obtained after cooling.

[0032] By employing the above technical solution, this preparation method controls the microstructure and chemical composition of the material through stepwise control of polymerization, emulsification, and heat treatment processes. The synergistic mechanism of each step is as follows:

[0033] Prepolymerization and grafting stage: First, a phenolic prepolymer containing hydroxymethyl groups is generated under alkaline conditions. Then, the temperature is lowered and a vinyl-containing metallocene precursor is introduced. The active sites in the prepolymer react with the vinyl groups to chemically bond the metal center to the polymer chain.

[0034] Emulsification and curing stage: Under the action of the dispersant, the metal-grafted prepolymer is dispersed into micron-sized droplets, and the block copolymer assembles inside the droplets to form a mesoporous template. Hexamethylenetetramine decomposes to release ammonia and formaldehyde, promoting resin crosslinking, curing, and shaping.

[0035] Multi-stage heat treatment stages:

[0036] Oxidation treatment: Low-temperature oxidation further crosslinks and cyclizes the polymer spheres, improving thermal stability.

[0037] Carbonization: At high temperatures, the organic framework is transformed into a carbon framework, the metal precursor decomposes, and the metal atoms, restricted by chemical bonds, cannot migrate long distances and are captured by the surrounding enriched nitrogen atoms.

[0038] Steam activation: Steam reacts with amorphous carbon to form new micropores on the carbon skeleton, increasing the specific surface area and exposing internal metal-nitrogen active sites.

[0039] Preferably, in step S1, the alkaline aqueous solution is a sodium hydroxide aqueous solution, and the pH value of the system is adjusted to 8.5-10.0; in step S2, the temperature of the prepolymerization reaction is 75-85℃, and the reaction time is 1.5-2.5 hours.

[0040] By adopting the above technical solution, a weakly alkaline environment is beneficial for controlling the polycondensation rate of phenolic resin, forming a prepolymer with suitable viscosity, which is conducive to subsequent emulsification and dispersion.

[0041] Preferably, in step S3, the prepolymer temperature is reduced to 55-65°C; the vinyl-containing metallocene precursor is pre-dissolved in anhydrous ethanol; and the stirring grafting time is 20-40 minutes.

[0042] By adopting the above technical solution, the cooling treatment reduces the reactivity of the prepolymer and prevents localized violent reactions when the metal precursor is added; the ethanol solvent assists the metal precursor to be uniformly dispersed and penetrate into the molecular chains of the prepolymer.

[0043] Preferably, in step S5, the specific process parameters for the multi-stage heat treatment are as follows:

[0044] Oxidation treatment: Heat to 380-400℃ at a heating rate of 1-3℃ / min, and hold for 0.5-1.5 hours;

[0045] Carbonization treatment: Heat to 800-850℃ at a heating rate of 1-3℃ / min, and hold for 1.5-3.5 hours;

[0046] Activation treatment: Heat to 800-825℃ at a heating rate of 3-5℃ / min, control the mass ratio of water vapor to carbonized material to be (3-27):1, and the activation time is 0.5-1.5 hours.

[0047] By adopting the above technical solution, the oxidation temperature is controlled at 380-400℃ to preserve the skeleton structure; by controlling the ratio of water vapor to carbonized material and the activation time, the pore expansion effect and carbon yield are balanced, and structural collapse is prevented due to over-activation.

[0048] Preferably, in step S4, the stirring and emulsification speed is 450-550 rpm, and the emulsification time is 15-25 minutes; the heating and curing temperature is 85-95℃, and the curing time is 2-4 hours.

[0049] By adopting the above technical solutions, controlling the shear rate and emulsification time ensures the uniformity of droplet size; controlling the curing temperature and time ensures the complete cross-linking of resin balls, giving them the mechanical strength to withstand high-temperature treatment.

[0050] This invention provides a nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms and a method for its preparation. It has the following beneficial effects:

[0051] 1. This invention selects a vinyl-containing metal precursor to participate in the polycondensation reaction of phenolic resin, and uses covalent bonds to anchor the metal complex in situ onto the polymer backbone. This chemical bonding effectively restricts the thermal migration of metal atoms during high-temperature carbonization, prevents the aggregation of metal particles, and thus achieves high dispersion loading of metal single atoms in the carbon substrate, effectively improving the utilization rate of active sites and cycle stability of the material.

[0052] 2. This invention employs a process combining soft template guidance and steam activation to construct a highly developed hierarchical pore structure. The mesoporous channels formed by the pyrolysis of the amphiphilic block copolymer effectively shorten the transport path of electrolyte ions, while controlled steam etching generates abundant micropores on the carbon walls and increases the specific surface area. This synergistic structure of mesopores and micropores provides ample charge storage sites and meets the requirements for rapid ion transport under high current densities.

[0053] 3. This invention utilizes aminophenol as a carbon-nitrogen dual source, combined with metal single-atom sites, to effectively improve the electrochemical performance of carbon materials. Uniform doping of nitrogen atoms improves the wettability and conductivity of the material surface. At the same time, the active sites of metal, nitrogen, and carbon, as well as nitrogen-containing functional groups, provide additional pseudocapacitance through redox reactions, enabling the resulting material to possess both high specific capacitance and excellent rate retention in supercapacitor applications. Attached Figure Description

[0054] Figure 1 The nitrogen adsorption-desorption curve of the mesoporous carbon material prepared in Example 1 of the present invention is shown.

[0055] Figure 2 The pore size distribution diagram is shown for the mesoporous carbon material prepared in Example 1 of the present invention.

[0056] Figure 3 The nitrogen adsorption-desorption curve of the mesoporous carbon material prepared in Example 2 of the present invention is shown.

[0057] Figure 4 The pore size distribution diagram is shown for the mesoporous carbon material prepared in Example 2 of the present invention.

[0058] Figure 5 The nitrogen adsorption-desorption curve of the mesoporous carbon material prepared in Example 3 of the present invention is shown.

[0059] Figure 6 The pore size distribution diagram is shown for the mesoporous carbon material prepared in Example 3 of the present invention.

[0060] Figure 7 The nitrogen adsorption-desorption curve of the mesoporous carbon material prepared in Example 4 of the present invention is shown.

[0061] Figure 8 The pore size distribution diagram is shown for the mesoporous carbon material prepared in Example 4 of the present invention.

[0062] Figure 9 The constant current charge-discharge curve of the mesoporous carbon material prepared in Example 1 of the present invention is shown. Detailed Implementation

[0063] The technical solutions of the present invention will be clearly and completely described below with reference to embodiments, comparative examples, and test examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0064] Examples 1-5: Example 1

[0065] This embodiment provides a nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms and a preparation method thereof, including the following steps:

[0066] S1. Dissolve 50g of phenol and 10g of p-aminophenol in 21mL of 10% sodium hydroxide aqueous solution and stir at 60℃ for 30min until the solid is completely dissolved.

[0067] S2. Slowly add 108 mL of 37% formaldehyde aqueous solution to the solution obtained in step S1. After the addition is complete, heat to 80℃ and react for 2 hours to obtain a brownish-red viscous prepolymer.

[0068] S3. Cool the prepolymer obtained in step S2 to 60°C, add a solution prepared by dissolving 0.5g of vinyl ferrocene in 5mL of anhydrous ethanol, and stir at 300rpm for 30 minutes to allow the metal precursor to react fully.

[0069] S4. Add 6.25g of pore-forming agent F127 and 500mL of 1% polyvinyl alcohol aqueous solution to the reactants obtained in step S3. Adjust the stirring speed to 550rpm and stir and emulsify for 20 minutes. Then add 7.5g of hexamethylenetetramine and heat to 90℃ to cure for 3 hours. After the reaction is complete, filter the product, wash it with deionized water and ethanol, and dry it in a vacuum drying oven to obtain phenolic resin balls.

[0070] S5. Place the phenolic resin balls obtained in step S4 in a tube furnace and oxidize them for 1 hour at a heating rate of 2℃ / min in air atmosphere to 400℃. Then switch to nitrogen atmosphere and carbonize them for 2 hours at a heating rate of 2℃ / min to 800℃. Next, introduce water vapor and control the mass ratio of water vapor to carbonized material to be 14:1. Heat the material to 825℃ at a heating rate of 4℃ / min under nitrogen protection and activate it at this temperature for 1 hour. After naturally cooling to room temperature, the nitrogen-doped spherical mesoporous carbon material rich in metal single atoms is obtained. Example 2

[0071] This embodiment provides a nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms and its preparation method. The difference between this embodiment and Embodiment 1 lies in the adjustment of some raw material ratios and carbonization activation process parameters to verify the applicability of the process range. The method includes the following steps:

[0072] S1. Dissolve 50g of phenol and 12g of p-aminophenol (mass ratio approximately 5:1.2) in 21mL of 10% sodium hydroxide aqueous solution (controlling the pH value to 10.0), and stir at 60℃ for 30min until the solid is completely dissolved.

[0073] S2. Slowly add 108 mL of 37% formaldehyde aqueous solution to the solution obtained in step S1. After the addition is complete, heat to 80°C and react for 2 hours to obtain the prepolymer.

[0074] S3. Cool the prepolymer obtained in step S2 to 60°C, add a solution prepared by dissolving 0.5g of vinyl ferrocene in 5mL of anhydrous ethanol, and stir at 300rpm for 30 minutes.

[0075] S4. Add 6.25g of pore-forming agent F127 (the mass ratio of pore-forming agent to phenol is approximately 1:9) and 500mL of 3% polyvinyl alcohol aqueous solution to the reactants obtained in step S3. Adjust the stirring speed to 550rpm and stir and emulsify for 20 minutes. Then add 7.5g of hexamethylenetetramine (approximately 15% of the resin solid content). Heat to 90℃ and cure for 3 hours. The product is filtered, washed, and vacuum dried to obtain phenolic resin balls.

[0076] S5. Place the phenolic resin balls obtained in step S4 in a tube furnace and oxidize them for 1 hour at a heating rate of 2℃ / min in air atmosphere to 400℃. Then switch to nitrogen atmosphere and carbonize them for 2 hours at a heating rate of 2℃ / min to 800℃. Next, introduce water vapor and control the mass ratio of water vapor to carbonized material to be 22:1. Heat the material to 825℃ at a heating rate of 4℃ / min under nitrogen protection and activate it at this temperature for 1.0 hour. After naturally cooling to room temperature, the nitrogen-doped spherical mesoporous carbon material rich in metal single atoms is obtained. Example 3

[0077] This embodiment provides a nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms and a preparation method thereof, including the following steps:

[0078] S1. Dissolve 50g of phenol and 10g of m-aminophenol (mass ratio 5:1) in 21mL of 10% sodium hydroxide aqueous solution and stir at 60℃ for 30min until the solid is completely dissolved.

[0079] S2. Slowly add 108 mL of 37% formaldehyde aqueous solution to the solution obtained in step S1. After the addition is complete, heat to 80°C and react for 2 hours to obtain the prepolymer.

[0080] S3. Cool the prepolymer obtained in step S2 to 60°C, add a solution prepared by dissolving 0.5g of vinyl ferrocene in 5mL of anhydrous ethanol, and stir at 300rpm for 30 minutes.

[0081] S4. Add 6.25g of pore-forming agent F127 and 500mL of 1% polyvinyl alcohol aqueous solution to the reactants obtained in step S3. Adjust the stirring speed to 550rpm and stir and emulsify for 20 minutes. Then add 7.5g of hexamethylenetetramine and heat to 90℃ to cure for 3 hours. The product is filtered, washed and vacuum dried to obtain phenolic resin balls.

[0082] S5. Place the phenolic resin balls obtained in step S4 in a tube furnace and oxidize them for 1 hour at a heating rate of 2℃ / min in air atmosphere to 400℃. Then switch to nitrogen atmosphere and carbonize them for 2 hours at a heating rate of 2℃ / min to 800℃. Next, introduce water vapor and control the mass ratio of water vapor to carbonized material to be 27:1. Heat the material to 825℃ at a heating rate of 4℃ / min under nitrogen protection and activate it at this temperature for 1 hour. After naturally cooling to room temperature, the nitrogen-doped spherical mesoporous carbon material rich in metal single atoms is obtained. Example 4

[0083] This embodiment provides a nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms and its preparation method. The difference from Embodiment 1 is that it uses vinyl cobaltene as a metal precursor and adjusts the water vapor activation temperature to verify the feasibility of different metal single-atom loadings and activation conditions. The method includes the following steps:

[0084] S1. Dissolve 50g of phenol and 10g of p-aminophenol (mass ratio 5:1) in 21mL of 10% sodium hydroxide aqueous solution and stir at 60℃ for 30min until the solid is completely dissolved.

[0085] S2. Slowly add 108 mL of 37% formaldehyde aqueous solution to the solution obtained in step S1. After the addition is complete, heat to 80°C and react for 2 hours to obtain the prepolymer.

[0086] S3. Cool the prepolymer obtained in step S2 to 60°C, add a solution prepared by dissolving 0.5g of vinyl cobalt oxide in 5mL of anhydrous ethanol, stir at 300rpm for 30 minutes, and perform in-situ grafting using double bonds.

[0087] S4. Add 6.25g of pore-forming agent F127 and 500mL of 1% polyvinyl alcohol aqueous solution to the reactants obtained in step S3. Adjust the stirring speed to 550rpm and stir and emulsify for 20 minutes. Then add 7.5g of hexamethylenetetramine and heat to 90℃ to cure for 3 hours. The product is filtered, washed and vacuum dried to obtain phenolic resin balls.

[0088] S5. Place the phenolic resin balls obtained in step S4 in a tube furnace and oxidize them for 1 hour at a heating rate of 2℃ / min in air atmosphere to 400℃. Then switch to nitrogen atmosphere and carbonize them for 2 hours at a heating rate of 2℃ / min to 800℃. Next, introduce water vapor and control the mass ratio of water vapor to carbonized material to be 27:1. Heat the material to 810℃ at a heating rate of 4℃ / min under nitrogen protection and activate it at this temperature for 1 hour. After naturally cooling to room temperature, the nitrogen-doped spherical mesoporous carbon material rich in metal single atoms is obtained. Example 5

[0089] This embodiment provides a nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms and its preparation method. The difference between this embodiment and Embodiment 1 lies in the use of a lower pore-forming agent ratio, a different oxidation carbonization temperature, and a lower water vapor activation ratio. The method includes the following steps:

[0090] S1. Prepare a sodium hydroxide aqueous solution with a pH of 8.5. Add 50g of phenol and 10g of p-aminophenol (mass ratio of 5:1) to the solution and stir at 60°C until the solid is completely dissolved.

[0091] S2. Slowly add 108 mL of 37% formaldehyde aqueous solution to the solution obtained in step S1. After the addition is complete, heat to 80°C and react for 2 hours to obtain the prepolymer.

[0092] S3. Cool the prepolymer obtained in step S2 to 60°C, add a solution prepared by dissolving 0.5g of vinyl ferrocene in 5mL of anhydrous ethanol, and stir at 300rpm for 30 minutes.

[0093] S4. Add 7.14g of pore-forming agent F127 (the mass ratio of pore-forming agent to phenol is approximately 1:7) and 500mL of 1% polyvinyl alcohol aqueous solution to the reactants obtained in step S3. Adjust the stirring speed to 450rpm and stir and emulsify for 20 minutes. Then add 5.0g of hexamethylenetetramine (approximately 10% of the resin solid content). Heat to 90℃ and cure for 3 hours. The product is filtered, washed, and vacuum dried to obtain phenolic resin balls.

[0094] S5. Place the phenolic resin balls obtained in step S4 in a tube furnace and oxidize them for 1 hour at a heating rate of 2℃ / min in air atmosphere to 380℃. Then switch to nitrogen atmosphere and carbonize them for 3 hours at a heating rate of 2℃ / min to 850℃. Next, introduce water vapor and control the mass ratio of water vapor to carbonized material to be 3:1. Heat the material to 800℃ at a heating rate of 4℃ / min under nitrogen protection and activate it at this temperature for 0.5 hours. After naturally cooling to room temperature, the nitrogen-doped spherical mesoporous carbon material rich in metal single atoms is obtained.

[0095] Comparative Examples 1-4:

[0096] Comparative Example 1:

[0097] Compared with Example 1, the difference is that in step S3, vinyl ferrocene is replaced with an equimolar amount of ferrocene without vinyl functional groups to verify the effect of in-situ vinyl bonding on the dispersion of metal single atoms and the conductivity of the material; all other aspects are the same.

[0098] Comparative Example 2:

[0099] Compared with Example 1, the difference is that p-aminophenol was not added in step S1, but was replaced with an equal mass of phenol (i.e., the total amount of phenol used was 60g) to verify the contribution of p-aminophenol as an endogenous nitrogen source to the specific capacitance and cycle stability of the material. All other aspects are the same.

[0100] Comparative Example 3:

[0101] Compared with Example 1, the difference is that pore-forming agent F127 was not added in step S4 to verify the importance of the soft template agent in forming a mesoporous structure and improving the rate performance; all other steps are the same.

[0102] Comparative Example 4:

[0103] Compared with Example 1, the difference is that in step S1, the sodium hydroxide aqueous solution is replaced with hydrochloric acid aqueous solution and the pH value is adjusted to 2.0, that is, the polymerization reaction is carried out under acidic conditions to verify the advantage of the alkaline catalytic system in regulating the spherical morphology and pore structure. All other aspects are the same.

[0104] Test Example 1-2:

[0105] Test Example 1: Characterization of Physicochemical Properties and Microstructure

[0106] Experimental steps:

[0107] The carbon materials prepared in Examples 1-5 and Comparative Examples 1-4 were characterized by their physicochemical properties. Field emission scanning electron microscopy was used to observe the surface morphology and particle size of the samples; transmission electron microscopy and high-angle annular dark-field scanning transmission electron microscopy were used to observe the internal pore structure and metal element distribution; X-ray diffraction was used to analyze the crystal structure and degree of graphitization; and laser Raman spectroscopy was used to characterize the degree of carbon structural defects, recording the D peak (approximately 1350 cm⁻¹). -1 ) and G peak (approximately 1580cm) -1The intensity ratio was determined. Nitrogen adsorption-desorption tests were conducted at 77 K using a fully automated specific surface area and pore size analyzer. The specific surface area was calculated based on the Brunauer-Emmett-Teller equation, the pore size distribution and mesopore volume were calculated based on the Barrett-Joyner-Halenda model, and the micropore volume was calculated using the t-plot method.

[0108] The physical parameter data obtained from the test are shown in the table below:

[0109]

[0110] Conclusion Analysis:

[0111] See attached document Figure 1-8 Based on the data in Table 1 and the electron microscopy results, the water vapor activation conditions have a significant impact on the pore parameters of the material. In Examples 1 and 2, as the amount of water vapor increased, the specific surface area decreased from 1931.4 m² / s². 2 / g increased to 2145.7m 2 The average pore size increased by g, indicating that increasing the water vapor content promoted pore expansion and the formation of new micropores. The total pore volume in Example 3 further increased to 1.31 cm³. 3 / g, the average pore size increased to 2.38nm, but the specific surface area decreased to 2088.3m². 2 / g. This indicates that the high concentration of water vapor has a strong etching effect, causing some micropore walls to ablate and merge into mesopores, thus reducing the number of micropores. Comparing Example 3 and Example 4, after lowering the activation temperature in Example 4, the specific surface area and average pore size were both lower than those in Example 3, indicating that lowering the temperature inhibited the water vapor activation reaction rate and prevented excessive pore widening.

[0112] Compared with Example 1, Comparative Example 3 has a specific surface area of ​​only 856.4 m². 2 / g, with a mesoporous content of 12.4%, confirming that the micelle occupancy effect of F127 in the aqueous phase is key to the formation of mesoporous channels. In terms of morphology, Example 1 showed uniform spherical shapes, while Comparative Example 4 exhibited irregular blocky shapes, indicating that an alkaline environment favors the spherical formation of the hydroxymethyl precursor in the PVA dispersion, while acidic conditions tend towards linear polycondensation. Regarding structural defects, the ID / IG value of Example 1 was 1.02, higher than that of Comparative Example 1 (0.92), indicating that the introduction of metal centers through vinyl copolymerization provides better dispersibility compared to physical mixing and induces more defect sites in the carbon substrate.

[0113] Test Example 2: Electrochemical Energy Storage Performance Test

[0114] Experimental steps:

[0115] The electrochemical performance of the prepared carbon material was tested using a three-electrode system. The working electrode was prepared as follows: the carbon material to be tested, acetylene black, and polytetrafluoroethylene emulsion (60% solid content) were mixed in a mass ratio of 8:1:1, dispersed with ethanol to form a slurry, and coated onto a 1cm×1cm nickel foam current collector (coating amount 3-5mg). After vacuum drying at 80℃ for 12 hours, it was pressed into a sheet at 10MPa. The tests were conducted using an electrochemical workstation (CHI660E), with the prepared nickel foam electrode as the working electrode, a platinum sheet as the counter electrode, and an Hg / HgO electrode as the reference electrode. The electrolyte was a 6mol / L potassium hydroxide aqueous solution. Constant current charge-discharge tests were performed within a voltage window of -1.0V to 0V at current densities ranging from 1A / g to 20A / g, and the specific capacitance was calculated based on the discharge time. Continuous charge-discharge cycles were performed at a current density of 5A / g, and the capacitance retention rate was recorded.

[0116] The electrochemical performance data obtained from the tests are shown in the table below:

[0117]

[0118] Conclusion Analysis:

[0119] See attached document Figure 9 Table 2 shows that the specific capacitance of Examples 1 to 4 all exceeded 340 F / g at a current density of 1 A / g. Example 2 exhibited the highest specific capacitance at 368.1 F / g, superior to Example 1's 342.5 F / g. This was attributed to the 1:22 activation ratio achieving the highest specific surface area, increasing the adsorption sites for electrolyte ions. Although Example 3 had the largest pore volume and a rate retention rate comparable to Example 2, its specific capacitance and cycle stability decreased slightly, indicating that over-activation reduces the material's bulk density or localized conductivity. In Example 4, after lowering the activation temperature, the specific capacitance and cycle stability recovered to levels close to those of Example 1, demonstrating that lowering the temperature at higher water vapor flow rates helps balance pore structure and framework stability.

[0120] In terms of rate performance, Example 1 maintained a capacitance retention of 75.5% at 20 A / g, higher than Comparative Example 3 without F127, confirming that the mesoporous structure shortens the ion diffusion path and improves the utilization of the active surface under high current. Regarding cycle stability, Example 1 was superior to Comparative Example 1. Example 1 utilized vinyl ferrocene for in-situ grafting via covalent bonds, resulting in stable anchoring of metal atoms in the carbon lattice after carbonization; in Comparative Example 1, the ferrocene was physically adsorbed, and aggregation or shedding during cycling easily led to capacity decay. Furthermore, Comparative Example 2 had a specific capacitance of 215.3 F / g, lower than Example 1, confirming that nitrogen doping improved the surface wettability of the material and contributed pseudocapacitance.

Claims

1. A nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms, characterized in that, The carbon material is made from raw materials comprising the following parts by weight: 45-55 parts of phenol; 9-13 parts of aminophenol; 100-120 parts of a 37% formaldehyde aqueous solution; 0.4-0.6 parts of a vinyl-containing metallocene precursor; 6-8 parts of triblock copolymer pore-forming agent; 4.5-8.0 parts of hexamethylenetetramine.

2. The nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms according to claim 1, characterized in that, The aminophenol is selected from one of p-aminophenol and m-aminophenol; the vinyl-containing metallocene precursor is selected from one of vinyl ferrocene and vinyl cobalt cadmium.

3. The nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms according to claim 1, characterized in that, The pore-forming agent of the triblock copolymer is a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer; the raw materials also include a dispersant, which is a polyvinyl alcohol aqueous solution with a mass concentration of 1%-3%.

4. The nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms according to claim 1, characterized in that, The mass ratio of phenol to aminophenol in the raw materials is 5:(1-1.2); the mass ratio of the triblock copolymer pore-forming agent to phenol is 1:(7-9).

5. The nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms according to claim 1, characterized in that, The carbon material has a spherical morphology, and the metal single atoms are dispersed in the nitrogen-doped carbon framework through in-situ grafting.

6. A method for preparing a nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Phenol and aminophenol are dissolved in an alkaline aqueous solution to obtain a phenolamine solution; S2. Add formaldehyde aqueous solution dropwise to the solution obtained in step S1, and heat to carry out prepolymerization reaction to obtain prepolymer; S3. Lower the temperature of the prepolymer, add an alcohol solution containing a vinyl metallocene precursor, and stir to allow the metal precursor and prepolymer to undergo a grafting reaction. S4. Add a triblock copolymer pore-forming agent and dispersant solution to the reactants obtained in step S3, stir and emulsify, then add hexamethylenetetramine, heat and cure, and the product is post-treated to obtain phenolic resin balls. S5. The phenolic resin balls are subjected to multi-stage heat treatment: first, oxidation is carried out in an air atmosphere; then, carbonization is carried out in an inert atmosphere; then, water vapor is introduced for activation under inert atmosphere protection, and the carbon material is obtained after cooling.

7. The method for preparing a nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms according to claim 6, characterized in that, In step S1, the alkaline aqueous solution is a sodium hydroxide aqueous solution, and the pH value of the system is adjusted to 8.5-10.0; in step S2, the temperature of the prepolymerization reaction is 75-85℃, and the reaction time is 1.5-2.5 hours.

8. The method for preparing a nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms according to claim 6, characterized in that, In step S3, the prepolymer temperature is reduced to 55-65°C; the vinyl-containing metallocene precursor is pre-dissolved in anhydrous ethanol; and the stirring grafting time is 20-40 minutes.

9. The method for preparing a nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms according to claim 6, characterized in that, In step S5, the specific process parameters for the multi-stage heat treatment are as follows: Oxidation treatment: Heat to 380-400℃ at a heating rate of 1-3℃ / min, and hold for 0.5-1.5 hours; Carbonization treatment: Heat to 800-850℃ at a heating rate of 1-3℃ / min, and hold for 1.5-3.5 hours; Activation treatment: Heat to 800-825℃ at a heating rate of 3-5℃ / min, control the mass ratio of water vapor to carbonized material to be (3-27):1, and the activation time is 0.5-1.5 hours.

10. The method for preparing a nitrogen-doped spherical mesoporous carbon material with dispersed metal single atoms according to claim 6, characterized in that, In step S4, the stirring and emulsification speed is 450-550 rpm, and the emulsification time is 15-25 minutes; the heating and curing temperature is 85-95℃, and the curing time is 2-4 hours.

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