Composite nitrogen and phosphorus co-doped ordered mesoporous carbon and preparation method and application thereof

Abstract

The present application relates to the technical field of functionalized porous carbon material, and particularly relates to a composite nitrogen and phosphorus co-doped ordered mesoporous carbon as well as a preparation method and application thereof, comprising the following steps: preparing larch wood phenol liquefact by using a liquefaction method; mixing the larch wood phenol liquefact with NH4Cl and F127, adding formaldehyde to perform self-assembly, and preparing a precursor; performing hydrothermal treatment and heat treatment on the precursor to form ordered mesoporous carbon; performing NH4Cl and phytic acid activation treatment on the ordered mesoporous carbon to prepare nitrogen and phosphorus co-doped ordered mesoporous carbon; adding the nitrogen and phosphorus co-doped ordered mesoporous carbon, a surfactant and a silane coupling agent mixture into an ethanol aqueous solution, and stirring at room temperature; then adding a pyrrole monomer, and stirring and mixing to obtain the composite nitrogen and phosphorus co-doped ordered mesoporous carbon. The composite material constructed in the present application realizes synchronous improvement of energy density and cycle stability on the basis of maintaining the advantages of ordered mesoporous structure.

Description

Technical Field

[0001] This invention relates to the field of functionalized porous carbon materials technology, and in particular to a composite nitrogen-phosphorus co-doped ordered mesoporous carbon, its preparation method and application. Background Technology

[0002] Larch wood, as a typical coniferous forest resource, produces phenol liquefaction products rich in phenolic hydroxyl groups and aromatic structural units, exhibiting excellent carbon precursor properties. These biomass-derived carbon sources can be used to prepare porous carbon materials with hierarchical pore structures via a soft template method. Compared to traditional petroleum-based carbon sources, biomass liquefaction products are not only inexpensive and renewable but also retain the original oxygen / nitrogen heteroatoms of the wood, providing a structural basis for subsequent doping and modification. In contrast, while commercial activated carbon possesses a high specific surface area, its disordered pore structure severely limits ion transport kinetics, particularly in high-power applications such as supercapacitors.

[0003] Ordered mesoporous carbon materials have attracted much attention in the field of electrochemical energy storage due to their unique structural advantages. The disordered arrangement of mesopores in traditional hierarchical porous carbon hinders ion transport, leading to slow mass transfer processes. In contrast, ordered mesoporous carbon provides a linear transport path for electrolyte ions, and its high specific surface area and nitrogen doping synergistically enhance charge storage capacity. Furthermore, the conjugation of nitrogen atoms with the large π bonds in the carbon lattice through lone pair electrons further optimizes the material's electronic conductivity and surface activity. Soft template methods are the core approach for constructing ordered mesoporous structures. These methods form ordered mesoporous structures through the self-assembly of surfactants (such as block copolymers like F127 and P123) and carbon sources. Their advantage lies in the ability to precisely design pore morphology and size through solvent-mediated and kinetic control. However, traditional soft template methods rely on large amounts of surfactants, resulting in high costs; while hard template methods require the use of corrosive HF to remove the template, making the process complex and environmentally polluting.

[0004] Existing patent CN201410071782.8 discloses a method for preparing larch-based ordered mesoporous carbon using a soft template method. This technology uses larch wood chips as raw material, liquefying phenol and reacting it with formaldehyde to generate phenolic resin. Block copolymer F127 is selected as a soft template, and the reaction is carried out under acidic conditions to generate a larch-based ordered mesoporous carbon mesophase. Finally, the product is obtained by high-temperature calcination under nitrogen protection. This method successfully realizes the high-value utilization of biomass resources and prepares carbon materials with an ordered mesoporous structure. However, the existing technology still has the following technical defects: on the one hand, although nitrogen doping can introduce pseudocapacitive effects to a certain extent, its effect on improving the overall electrochemical performance of the material is limited, and it cannot meet the higher energy density requirements of high-performance energy storage devices; on the other hand, the carbon materials prepared by the existing technology have relatively inert surfaces, and during long-term electrochemical cycling, the material is prone to structural degradation, leading to specific capacitance decay and shortened cycle life, limiting its application in practical energy storage devices. Summary of the Invention

[0005] In view of this, the present invention proposes a composite nitrogen-phosphorus co-doped ordered mesoporous carbon, its preparation method and application, to solve the technical problems of the single energy storage mechanism of carbon materials and the difficulty in synergistically improving energy density and cycle stability due to structural degradation in the prior art.

[0006] The technical solution of this invention is achieved as follows: This invention provides a method for preparing composite nitrogen-phosphorus co-doped ordered mesoporous carbon, comprising the following steps: S1. Preparation of larch wood phenol liquefaction product by liquefaction method. S2. Phenol liquefaction of larch wood was mixed with NH4Cl and F127 in ethanol-HCl solution, and formaldehyde was added to carry out self-assembly to obtain the precursor. S3. The precursor is subjected to hydrothermal treatment and heat treatment to form ordered mesoporous carbon; S4. Ordered mesoporous carbon was activated by NH4Cl and phytic acid to obtain nitrogen-phosphorus co-doped ordered mesoporous carbon. S5. Add the nitrogen-phosphorus co-doped ordered mesoporous carbon, surfactant and silane coupling agent mixture to an ethanol aqueous solution, adjust the pH to 3-5, and stir at room temperature for 2-4 hours; then add pyrrole monomer, stir and mix, cool to 0-5℃, add ammonium persulfate solution dropwise, and continue the reaction in an ice-water bath for 6-12 hours to obtain composite nitrogen-phosphorus co-doped ordered mesoporous carbon.

[0007] Specifically, in step S1, liquefaction effectively degrades the complex fibrous structure of wood while preserving the original oxygen and nitrogen heteroatoms, providing a natural structural basis for subsequent heteroatom doping. In step S2, the phenolic hydroxyl groups in larch liquefaction react with formaldehyde under acidic conditions to form phenolic resin. NH4Cl acts as a structure directing agent and nitrogen source precursor, participating in the self-assembly process. F127 micelles act as a soft template, guiding the phenolic resin to arrange itself in an orderly manner around it, forming an organic-inorganic composite precursor with a periodic mesoporous structure. Compared to the traditional hard template method, this avoids the complex process of removing the template using corrosive HF. Compared to the pure soft template method, the introduction of NH4Cl improves structural stability and provides a source for nitrogen doping, achieving synergistic optimization of pore construction and heteroatom doping. In step S3, hydrothermal treatment further promotes the condensation and cross-linking of the organic components in the precursor, while the heat treatment stage promotes the carbonization of the organic matter to form ordered mesoporous carbon.

[0008] In step S4, NH4Cl decomposes at high temperature to produce NH3 and HCl gases. NH3 provides nitrogen doping, while HCl activates the carbon framework and expands the pore volume. Phytic acid decomposes during heat treatment to release phosphate groups. These phosphorus-containing species are incorporated into the carbon lattice in the form of phosphates, pyrophosphates, or elemental phosphorus, resulting in nitrogen-phosphorus co-doped ordered mesoporous carbon. In step S5, the silane coupling agent mixture undergoes hydrolysis and preliminary condensation under acidic conditions, forming a loose polysiloxane pre-network on the surface of the nitrogen-phosphorus co-doped carbon. Subsequently, the added pyrrole monomer is adsorbed onto the carbon surface modified by this pre-network and undergoes oxidative polymerization under the initiation of ammonium persulfate to form polypyrrole chains. The growth of the polypyrrole chains and the further condensation of the polysiloxane network proceed simultaneously, ultimately forming a three-dimensional network structure in which organic polypyrrole and inorganic polysiloxane interpenetrate.

[0009] Based on the above technical solutions, preferably, in step S1, the liquefaction of phenol in larch wood specifically includes the following processes: Larch wood powder was mixed with phenol and concentrated sulfuric acid and refluxed at 125-135℃ for 0.8-1.2 h to obtain a mixture. After cooling the mixture, methanol was added, filtered, and neutralized with 20% sodium hydroxide solution. After removing methanol and water, larch wood phenol liquefaction was obtained.

[0010] Under the catalysis of concentrated sulfuric acid, macromolecular polymers such as cellulose, hemicellulose, and lignin in larch wood undergo degradation, alcoholysis, and phenololysis reactions at high temperatures. Compared with traditional petroleum-based carbon sources, this biomass liquefaction product has advantages such as low cost, renewability, and environmental friendliness. At the same time, its abundant functional groups provide more reactive sites for constructing an ordered porous structure.

[0011] Based on the above technical solutions, the preferred mass-volume ratio of larch wood powder to phenol and concentrated sulfuric acid is 10g:45-55ml:2ml.

[0012] Based on the above technical solutions, preferably, in step S2, the mass ratio of larch wood phenol liquefaction, NH4Cl and F127 is 0.3g:0.5g:1.1-1.3g, and the concentration of HCl solution is 1.6-1.8M.

[0013] Based on the above technical solutions, preferably, in step S3, the temperature of the hydrothermal treatment is 145-155℃ and the time is 22-26h; The heat treatment includes: in a nitrogen atmosphere, at 4-6 °C·min −1 The sample was heated to 300-400℃ at a heating rate and held for 2.5-3.5 h; then heated at 8-12℃∙min. −1 The heating rate is increased to 750-850℃ and maintained for 1.5-2.5 hours.

[0014] The segmented heat treatment process ensures the controllability of the carbonization process and avoids structural collapse. The slow heating in the low-temperature stage protects the integrity of the mesoporous structure, while the high-temperature stage promotes the graphitization of the carbon skeleton and improves the conductivity of the material.

[0015] Based on the above technical solutions, preferably, in step S4, the mass ratio of ordered mesoporous carbon, NH4Cl and phytic acid is 1:(0.8-1.2):(0.3-0.8), the activation temperature is 750-850℃, and the time is 1.5-2.5h.

[0016] Based on the above technical solution, preferably, in step S5, the mass ratio of the nitrogen-phosphorus co-doped ordered mesoporous carbon, surfactant, and silane coupling agent mixture is 1:(0.01-0.05):(0.8-1.5), the amount of pyrrole monomer added is 0.5-1.2 times the mass of the nitrogen-phosphorus co-doped ordered mesoporous carbon, the amount of ammonium persulfate solution added is 0.8-1.5 times the mass of the pyrrole monomer, and the concentration of the ammonium persulfate solution is 0.1-0.2M.

[0017] Compared with single nitrogen doping, nitrogen-phosphorus co-doped materials achieve synergistic contributions from double-layer capacitance and pseudocapacitance in energy storage mechanism, significantly improving the energy density of the material.

[0018] Based on the above technical solution, preferably, in step S5, the surfactant is hexadecylammonium bromide, and the silane coupling agent mixture is methyltrimethoxysilane and (3-aminopropyl)triethoxysilane, with a mass ratio of methyltrimethoxysilane to (3-aminopropyl)triethoxysilane of (1.5-3):1.

[0019] Methyltrimethoxysilane molecules can form silanol groups upon hydrolysis, exhibiting high cross-linking activity and being used to construct rigid polysiloxane three-dimensional frameworks. (3-aminopropyl)triethoxysilane, on the other hand, has a dual function: its three ethoxy groups participate in the construction of siloxane networks, while the terminal amino group, as a functional group, can bind to nitrogen- and oxygen-containing functional groups on the surface of polypyrrole molecular chains and carbon substrates through various interactions such as hydrogen bonds and van der Waals forces.

[0020] The present invention also provides a composite nitrogen-phosphorus co-doped ordered mesoporous carbon prepared by the above preparation method.

[0021] The present invention also provides an application of composite nitrogen-phosphorus co-doped ordered mesoporous carbon, which is used as an electrode material for supercapacitors. The composite nitrogen-phosphorus co-doped ordered mesoporous carbon of the present invention, its preparation method, and its application have the following advantages over the prior art: (1) By introducing nitrogen-phosphorus co-doping and organic-inorganic hybrid interpenetrating network composite modification strategy, the present invention achieves diversified synergy of energy storage mechanisms. Compared with the existing technology that relies only on single nitrogen doping and double-layer capacitor energy storage, the composite material constructed by the present invention has a triple energy storage mechanism of double-layer capacitor, nitrogen-phosphorus pseudocapacitor and polypyrrole pseudocapacitor. While maintaining the advantages of ordered mesoporous structure, the energy density and cycle stability are simultaneously improved through synergistic effect.

[0022] (2) The mesoporous structure of the template agent is accurately replicated by using the soft template method through NH4Cl-assisted self-assembly technology, thereby controlling the pore size and pore volume. This process not only simplifies the preparation process but is also easy to operate. Through hydrothermal treatment and activation, larch wood phenol liquefaction, a natural and abundant forestry waste, is transformed into high-performance carbon material. The resulting material has a regular structure, large specific surface area, and regular pore structure. Through the doping of nitrogen and phosphorus elements, the structural characteristics and catalytic performance of the catalyst are further improved, the functional groups on the surface of the mesoporous carbon are enriched, and more catalytic reaction sites are provided. In addition, the low cost and renewable characteristics of the biomass precursor of this invention give the material significant environmental and economic advantages.

[0023] (3) By adopting phytic acid synergistic activation treatment, precise co-doping of nitrogen and phosphorus elements was achieved, which effectively enhanced the pseudocapacitive contribution of the material. Phytic acid, as a polyphosphate compound, decomposes and releases phosphate groups during pyrolysis, which are incorporated into the carbon lattice in the form of phosphate, pyrophosphate or elemental phosphorus to form CP bonds. This has a synergistic effect with the nitrogen doping provided by NH4Cl. The coexistence of the two heteroatoms forms more pseudocapacitive active sites, which significantly improves the energy storage performance compared with single nitrogen doped materials.

[0024] (4) The constructed polypyrrole-polysiloxane interpenetrating network structure achieves synergistic optimization of high energy density and excellent cycling stability. The rigid polysiloxane network can constrain the volume expansion of polypyrrole chains and prevent their structural degradation during long-term charge-discharge cycles. The interfacial bonding network constructed by the amino groups in (3-aminopropyl)triethoxysilane through hydrogen bonding further enhances the bonding strength between the coating and the carbon substrate. This enables the coating to provide abundant pseudocapacitance while effectively suppressing the peeling and performance degradation of the active coating, thus solving the problem of poor cycling stability of traditional conductive polymer composite materials. Attached Figure Description

[0025] 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.

[0026] Figure 1 This is an electron microscope image of the ordered mesoporous carbon prepared in Example 1 of the present invention. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1 This embodiment provides a composite nitrogen-phosphorus co-doped ordered mesoporous carbon and its preparation method, including the following steps: S1. Mix 100g of dried larch wood powder with 500ml of phenol and 20ml of concentrated sulfuric acid, reflux at 130℃ and stir for 1.0h to obtain a mixture; after cooling the mixture to room temperature, add 1000ml of methanol, filter and neutralize the filtrate with 20% sodium hydroxide solution, filter to remove the precipitate, and remove methanol and water by vacuum distillation at 40℃ to obtain larch wood phenol liquefaction. S2. Mix 30g of larch wood phenol liquefaction with 50g of NH4Cl and 120g of F127 in a 1000ml ethanol-HCl solution (total volume 7000ml). The concentration of the HCl solution is 1.7M. Stir at 100r / min for 30min at room temperature to form a homogeneous solution. Add 50-60mL of formaldehyde dropwise to this homogeneous solution and continue stirring at 100r / min for 2h to obtain the precursor. S3. Transfer the precursor to a polytetrafluoroethylene-lined autoclave. The sealed autoclave is hydrothermally treated at 150°C for 24 hours. After hydrothermal treatment, the precipitate is collected by centrifugation at 8000 rpm. The precipitate is washed three times each with deionized water and anhydrous ethanol. The washed precipitate is then dried at 80°C for 12 hours. Following this, heat treatment is performed, including heating at 5°C in a nitrogen atmosphere. −1 The sample was heated to 350 °C and held for 3.0 h at a heating rate of 10 °C·min. −1 The heating rate was increased to 800℃ and held for 2.0 h to form ordered mesoporous carbon; S4. Mix and grind 100g of ordered mesoporous carbon, 100g of NH4Cl and 55g of phytic acid, and then heat under a nitrogen atmosphere at 10℃∙min. −1 The temperature was increased to 800℃ and held for 2.0 h for activation treatment. After activation treatment, the sample was allowed to cool naturally to room temperature to obtain nitrogen and phosphorus co-doped ordered mesoporous carbon. S5. Add 100g of nitrogen-phosphorus co-doped ordered mesoporous carbon, 3g of hexadecyl ammonium bromide and 115g of silane coupling agent mixture to 1000ml of ethanol-water solution (ethanol to water volume ratio of 1:1). The silane coupling agent mixture is methyltrimethoxysilane and (3-aminopropyl)triethoxysilane in a mass ratio of 2.2:1. Adjust the pH to 3-5 and stir at room temperature for 3h. Then add 85g of pyrrole monomer, stir and mix, cool to 0-5℃, add 110g of ammonium persulfate solution (concentration of 0.15M) dropwise, and continue the reaction in an ice-water bath for 9h. After the reaction is completed, centrifuge to collect the precipitate, wash with deionized water and anhydrous ethanol, and vacuum dry to obtain composite nitrogen-phosphorus co-doped ordered mesoporous carbon.

[0029] Example 2 This embodiment provides a composite nitrogen-phosphorus co-doped ordered mesoporous carbon and its preparation method, including the following steps: S1. Mix 100g of dried larch wood powder with 450ml of phenol and 20ml of concentrated sulfuric acid, reflux at 125℃ and stir for 1.2h to obtain a mixture; after cooling the mixture to room temperature, add 1000ml of methanol, filter and neutralize the filtrate with 20% sodium hydroxide solution, filter to remove the precipitate, and remove methanol and water by vacuum distillation at 40℃ to obtain larch wood phenol liquefaction. S2. Mix 30g of larch wood phenol liquefaction with 50g of NH4Cl and 110g of F127 in a 1000ml ethanol-HCl solution (total volume 7000ml). The concentration of the HCl solution is 1.6M. Stir at 100r / min for 30min at room temperature to form a homogeneous solution. Add 50mL of formaldehyde dropwise to this homogeneous solution and continue stirring at 100r / min for 2h to obtain the precursor. S3. Transfer the precursor to a polytetrafluoroethylene-lined autoclave. The sealed autoclave is hydrothermally treated at 145°C for 26 hours. After hydrothermal treatment, the precipitate is collected by centrifugation at 8000 rpm. The precipitate is washed three times each with deionized water and anhydrous ethanol. The washed precipitate is then dried at 80°C for 12 hours. Following this, heat treatment is performed, including heating at 4°C in a nitrogen atmosphere. −1 The sample was heated to 300℃ and held for 3.5 h at a heating rate of 8℃∙min. −1 The heating rate was increased to 750℃ and held for 2.5 hours to form ordered mesoporous carbon; S4. Mix and grind 100g of ordered mesoporous carbon, 80g of NH4Cl and 30g of phytic acid, and then heat under a nitrogen atmosphere at 8℃∙min. −1 The heating rate was increased to 750℃ and held for 2.5h for activation treatment. After activation treatment, the sample was allowed to cool naturally to room temperature to obtain nitrogen and phosphorus co-doped ordered mesoporous carbon. S5. Add 100g of nitrogen-phosphorus co-doped ordered mesoporous carbon, 1g of hexadecyl ammonium bromide and 80g of silane coupling agent mixture to 1000ml of ethanol-water solution (ethanol to water volume ratio of 1:1). The silane coupling agent mixture is methyltrimethoxysilane and (3-aminopropyl)triethoxysilane in a mass ratio of 1.5:1. Adjust the pH to 3-5 and stir at room temperature for 2h. Then add 50g of pyrrole monomer, stir and mix, cool to 0-5℃, add 40g of ammonium persulfate solution (concentration of 0.2M) dropwise, and continue the reaction in an ice-water bath for 6h. After the reaction is completed, centrifuge to collect the precipitate, wash with deionized water and anhydrous ethanol, and vacuum dry to obtain composite nitrogen-phosphorus co-doped ordered mesoporous carbon.

[0030] Example 3 This embodiment provides a composite nitrogen-phosphorus co-doped ordered mesoporous carbon and its preparation method, including the following steps: S1. Mix 100g of dried larch wood powder with 550ml of phenol and 20ml of concentrated sulfuric acid, reflux at 135℃ and stir for 0.8h to obtain a mixture; after cooling the mixture to room temperature, add 1000ml of methanol, filter and neutralize the filtrate with 20% sodium hydroxide solution, filter to remove the precipitate, and remove methanol and water by vacuum distillation at 40℃ to obtain larch wood phenol liquefaction. S2. Mix 30g of larch wood phenol liquefaction with 50g of NH4Cl and 130g of F127 in a 1000ml ethanol-HCl solution (total volume 7000ml). The concentration of the HCl solution is 1.8M. Stir at 100r / min for 30min at room temperature to form a homogeneous solution. Add 60mL of formaldehyde dropwise to this homogeneous solution and continue stirring at 100r / min for 2h to obtain the precursor. S3. Transfer the precursor to a polytetrafluoroethylene-lined autoclave. The sealed autoclave is hydrothermally treated at 155°C for 22 hours. After hydrothermal treatment, the precipitate is collected by centrifugation at 8000 rpm. The precipitate is washed three times each with deionized water and anhydrous ethanol. The washed precipitate is then dried at 80°C for 12 hours. Following this, heat treatment is performed, including heating at 6°C in a nitrogen atmosphere. −1 The sample was heated to 400℃ at a heating rate and held for 2.5 h; then heated at 12℃∙min −1 The heating rate was increased to 850℃ and held for 1.5 hours to form ordered mesoporous carbon; S4. Mix and grind 100g of ordered mesoporous carbon, 120g of NH4Cl and 80g of phytic acid, and then heat under a nitrogen atmosphere at 12℃∙min. −1 The heating rate was increased to 850℃ and held for 1.5h for activation treatment. After activation treatment, the sample was allowed to cool naturally to room temperature to obtain nitrogen and phosphorus co-doped ordered mesoporous carbon. S5. Add 100g of nitrogen-phosphorus co-doped ordered mesoporous carbon, 5g of hexadecyl ammonium bromide and 150g of silane coupling agent mixture to 1000ml of ethanol-water solution (ethanol to water volume ratio of 1:1). The silane coupling agent mixture is methyltrimethoxysilane and (3-aminopropyl)triethoxysilane in a mass ratio of 3:1. Adjust the pH to 3-5 and stir at room temperature for 4h. Then add 120g of pyrrole monomer, stir and mix, cool to 0-5℃, add 180g of ammonium persulfate solution (concentration of 0.1M) dropwise, and continue the reaction in an ice-water bath for 12h. After the reaction is completed, centrifuge to collect the precipitate, wash with deionized water and anhydrous ethanol, and vacuum dry to obtain composite nitrogen-phosphorus co-doped ordered mesoporous carbon.

[0031] Comparative Example 1 This comparative example provides a composite nitrogen-phosphorus co-doped ordered mesoporous carbon and its preparation method. The preparation method is the same as in Example 1, except that phosphorus is not doped. Specifically, it includes the following steps: S1-S3 are the same as in Example 1; S4. Mix and grind 100g of ordered mesoporous carbon and 155g of NH4Cl, then heat under a nitrogen atmosphere at 10℃∙min. −1 The temperature was increased to 800℃ and held for 2.0 h for activation treatment. After activation treatment, the sample was allowed to cool naturally to room temperature to obtain nitrogen-doped ordered mesoporous carbon. S5. Add 100g of nitrogen-doped ordered mesoporous carbon, 3g of hexadecyl ammonium bromide and 115g of silane coupling agent mixture to 1000ml of ethanol-water solution (ethanol to water volume ratio of 1:1). The silane coupling agent mixture is methyltrimethoxysilane and (3-aminopropyl)triethoxysilane in a mass ratio of 2.2:1. Adjust the pH to 3-5 and stir at room temperature for 3h. Then add 85g of pyrrole monomer, stir and mix, cool to 0-5℃, add 110g of ammonium persulfate solution (concentration of 0.15M) dropwise, and continue the reaction in an ice-water bath for 9h. After the reaction is completed, centrifuge to collect the precipitate, wash with deionized water and anhydrous ethanol, and vacuum dry to obtain composite nitrogen-phosphorus co-doped ordered mesoporous carbon.

[0032] Comparative Example 2 This comparative example provides a composite nitrogen-phosphorus co-doped ordered mesoporous carbon and its preparation method. The preparation method is the same as in Example 1, except that pyrrole monomer is not added. The specific steps include: S1-S4 are the same as in Example 1; S5. Add 100g of nitrogen-phosphorus co-doped ordered mesoporous carbon, 3g of hexadecyl ammonium bromide and 115g of silane coupling agent mixture to 1000ml of ethanol-water solution (ethanol to water volume ratio of 1:1). The silane coupling agent mixture is methyltrimethoxysilane and (3-aminopropyl)triethoxysilane in a mass ratio of 2.2:1. Adjust the pH to 3-5, stir at room temperature for 3h. After the reaction is complete, centrifuge to collect the precipitate, wash with deionized water and anhydrous ethanol, and vacuum dry to obtain composite nitrogen-phosphorus co-doped ordered mesoporous carbon.

[0033] Comparative Example 3 This comparative example provides a composite nitrogen-phosphorus co-doped ordered mesoporous carbon and its preparation method. The preparation method is the same as in Example 1, except that a silane coupling agent mixture is not added. The specific steps include: S1-S4 are the same as in Example 1; S5. Add 100g of nitrogen-phosphorus co-doped ordered mesoporous carbon, 3g of hexadecyl ammonium bromide and 85g of pyrrole monomer to 1000ml of ethanol-water solution (ethanol to water volume ratio of 1:1), stir and mix, cool to 0-5℃, add 110g of ammonium persulfate solution (concentration of 0.15M), and continue to react in an ice-water bath for 9h. After the reaction is completed, centrifuge to collect the precipitate, wash with deionized water and anhydrous ethanol, and vacuum dry to obtain composite nitrogen-phosphorus co-doped ordered mesoporous carbon.

[0034] Comparative Example 4 This comparative example provides a composite nitrogen-phosphorus co-doped ordered mesoporous carbon and its preparation method. The preparation method is the same as in Example 1, except that (3-aminopropyl)triethoxysilane is not added. The specific steps include: S1-S4 are the same as in Example 1; S5. Add 100g of nitrogen-phosphorus co-doped ordered mesoporous carbon, 3g of hexadecylammonium bromide and 115g of methyltrimethoxysilane to 1000ml of ethanol-water solution (ethanol to water volume ratio of 1:1), adjust the pH to 3-5, and stir at room temperature for 3h; then add 85g of pyrrole monomer, stir and mix, cool to 0-5℃, add 110g of ammonium persulfate solution (concentration of 0.15M) dropwise, and continue the reaction in an ice-water bath for 9h. After the reaction is completed, centrifuge to collect the precipitate, wash with deionized water and anhydrous ethanol, and vacuum dry to obtain composite nitrogen-phosphorus co-doped ordered mesoporous carbon.

[0035] Performance testing The composite nitrogen-phosphorus co-doped ordered mesoporous carbons prepared in the examples and comparative examples were subjected to performance tests. The specific surface area, average pore size, and pore volume of the composite nitrogen-phosphorus co-doped ordered mesoporous carbon samples were tested using a TriStarII 3020 fully automated specific surface area and pore volume analyzer. The test results are shown in Table 1.

[0036] Table 1 BET Test Results

[0037] As shown in Table 1, the technical solution of this invention constructs an ordered mesoporous structure using the NH4Cl-assisted soft template method, and then significantly increases the specific surface area and total pore volume of the material through a composite modification strategy involving nitrogen-phosphorus co-doping and organic-inorganic hybrid interpenetrating networks. Figure 1 As shown, Figure 1The images shown are electron microscope (EM) images of the ordered mesoporous carbon prepared in Example 1. Figure (a) is a low-magnification morphology image, while Figures (b) and (c) are high-magnification morphology images, clearly demonstrating the regular mesoporous structure inside the mesoporous carbon. The data from Comparative Examples 1-4 are generally lower than those of the examples. In Comparative Example 1, due to the lack of phytic acid for synergistic activation, the activation effect of NH4Cl alone reduces the porosity and specific surface area. In Comparative Example 2, without polypyrrole filling, the pore structure of the carbon material is more open, resulting in an increase in specific surface area. This indicates that the introduction of polypyrrole does indeed moderately reduce pore parameters, but this sacrifice is for obtaining superior electrochemical performance. In Comparative Example 3, lacking the protection and guidance of the polysiloxane network, polypyrrole directly polymerizes disorderly on the carbon surface, easily forming large molecular aggregates that block the pore entrances, destroying the ordered mesoporous structure, and consequently leading to a decrease in parameters such as specific surface area. In Comparative Example 4, when APTES is missing, the polypyrrole chains lack effective interfacial anchoring, easily agglomerating in the pores to form large polymer particles, blocking the pores and reducing pore utilization efficiency.

[0038] Electrochemical performance testing: Electrochemical measurements were performed on a CHI 760 electrochemical workstation (Shanghai Chenhua Instrument Co., Ltd., China). The three-electrode system was tested using a Hg / HgO electrode and a Pt sheet as the reference and counter electrodes, respectively, with a 6 M KOH solution as the electrolyte. The working electrode was prepared by uniformly mixing porous carbon sample (80 mg), polyvinylidene fluoride, and acetylene black in a mortar at a mass ratio of 8:1:1. An appropriate amount of N-methylpyrrolidone-2-one (NMP) was added to the mixture, and it was ground until a slurry-like consistency was achieved. A suitable amount of the slurry was evenly spread on carbon cloth (1 cm × 1 cm) and dried at 80 ℃ for 12 h. The mass loading of the composite nitrogen-phosphorus co-doped ordered mesoporous carbon was 1.5 mg, the test voltage was -1 to 0 V, the test current density was 1 A / g, and the long-cycle charge-discharge cycle was 20,000 times.

[0039] The specific capacitance of the composite nitrogen-phosphorus co-doped ordered mesoporous carbon is obtained from the following equation:

[0040] Where I and Δt are the applied discharge current and discharge time, respectively; m is the mass of the composite nitrogen-phosphorus co-doped ordered mesoporous carbon; and ΔV is the discharge voltage range. The test results are shown in Table 2.

[0041] Table 2 Electrochemical performance test results

[0042] As shown in Table 2, the nitrogen-phosphorus co-doped ordered mesoporous carbon prepared by the technical solution of this invention, as an electrode material for supercapacitors, exhibits excellent electrochemical performance, especially the nitrogen-doped ordered mesoporous carbon. In Comparative Example 1, the lack of phosphorus significantly affected the pseudocapacitive performance due to the synergistic doping effect. Although the nitrogen content increased slightly due to the disappearance of the phosphorus dilution effect, single nitrogen doping could not achieve the synergistic effect of nitrogen-phosphorus co-doping, leading to a significant decrease in specific capacitance. The slight decrease in cycle stability was due to the lack of phosphorus doping contributing to the stability of the carbon framework structure. In Comparative Example 2, the absence of polypyrrole resulted in a significant decrease in specific capacitance. In Comparative Example 3, the lack of mechanical constraint protection from the polysiloxane network caused severe volume expansion and contraction of polypyrrole during charge and discharge, leading to molecular chain breakage, inactivation of active sites, and destruction of the electrode material structure, resulting in a sharp deterioration in cycle stability. In Comparative Example 4, the absence of (3-aminopropyl)triethoxysilane, although still forming a polysiloxane framework to provide some structural stability, significantly reduced the synergistic effect between components due to the lack of functional linking groups, resulting in a double decrease in specific capacitance and cycle stability.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing composite nitrogen-phosphorus co-doped ordered mesoporous carbon, characterized in that: Includes the following steps: S1. Preparation of larch wood phenol liquefaction by liquefaction method; S2. Phenol liquefaction of larch wood was mixed with NH4Cl and F127 in ethanol-HCl solution, and formaldehyde was added to carry out self-assembly to obtain the precursor. S3. The precursor is subjected to hydrothermal treatment and heat treatment to form ordered mesoporous carbon; wherein the hydrothermal treatment temperature is 145-155℃ and the time is 22-26h; the heat treatment includes: in a nitrogen atmosphere, at 4-6℃ min 1 The sample was heated to 300-400℃ at a certain heating rate and held for 2.5-3.5 hours; then heated at 8-12℃. min 1 The heating rate is increased to 750-850℃ and maintained for 1.5-2.5 hours; S4. Activate the ordered mesoporous carbon with NH4Cl and phytic acid to obtain nitrogen-phosphorus co-doped ordered mesoporous carbon; the mass ratio of ordered mesoporous carbon, NH4Cl and phytic acid is 1:0.8-1.2:0.3-0.8, the activation temperature is 750-850℃ and the time is 1.5-2.5h. S5. A mixture of nitrogen-phosphorus co-doped ordered mesoporous carbon, surfactant, and silane coupling agent is added to an ethanol-water solution, the pH is adjusted to 3-5, and the mixture is stirred at room temperature for 2-4 hours. Then, pyrrole monomer is added, the mixture is stirred and mixed, the temperature is lowered to 0-5℃, ammonium persulfate solution is added dropwise, and the reaction continues in an ice-water bath for 6-12 hours to obtain composite nitrogen-phosphorus co-doped ordered mesoporous carbon. The mass ratio of the nitrogen-phosphorus co-doped ordered mesoporous carbon, surfactant, and silane coupling agent mixture is 1:0.01-0.05:0.

8. -1.5, the amount of pyrrole monomer added is 0.5-1.2 times the mass of nitrogen-phosphorus co-doped ordered mesoporous carbon, the amount of ammonium persulfate solution added is 0.8-1.5 times the mass of pyrrole monomer, and the concentration of ammonium persulfate solution is 0.1-0.2M; the surfactant is hexadecylammonium bromide, and the silane coupling agent mixture is methyltrimethoxysilane and (3-aminopropyl)triethoxysilane, with a mass ratio of methyltrimethoxysilane to (3-aminopropyl)triethoxysilane of 1.5-3:

1.

2. The method for preparing a composite nitrogen-phosphorus co-doped ordered mesoporous carbon as described in claim 1, characterized in that: In step S1, the liquefaction of phenol in larch wood specifically includes the following processes: Larch wood powder was mixed with phenol and concentrated sulfuric acid and refluxed at 125-135℃ for 0.8-1.2 h to obtain a mixture. After cooling the mixture, methanol was added, filtered, and neutralized with 20% sodium hydroxide solution. After removing methanol and water, larch wood phenol liquefaction was obtained.

3. The method for preparing a composite nitrogen-phosphorus co-doped ordered mesoporous carbon as described in claim 2, characterized in that: The mass-volume ratio of larch wood powder to phenol and concentrated sulfuric acid is 10g:45-55ml:2ml.

4. The method for preparing a composite nitrogen-phosphorus co-doped ordered mesoporous carbon as described in claim 1, characterized in that: In step S2, the mass ratio of larch wood phenol liquefaction, NH4Cl and F127 is 0.3g:0.5g:1.1-1.3g, and the concentration of HCl solution is 1.6-1.8M.

5. A composite nitrogen-phosphorus co-doped ordered mesoporous carbon prepared by the preparation method according to any one of claims 1-4.

6. The application of the composite nitrogen-phosphorus co-doped ordered mesoporous carbon as described in claim 5, characterized in that: The composite nitrogen-phosphorus co-doped ordered mesoporous carbon is used as an electrode material for supercapacitors.

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