A method for preparing nitrogen and phosphorus co-doped carbon nanotube material with hierarchical pore structure

Abstract

The present invention discloses a method for preparing a nitrogen and phosphorus co-doped carbon nanotube material with a hierarchical pore structure, which belongs to the field of functional porous materials. The carbon nanotubes prepared by the process of the present invention are highly dispersible and nanoscale, and successfully realize the co-doping of nitrogen and phosphorus on the surface to form rich active sites. The obtained material has a high specific surface area and a porous structure with coexistence of micropores, mesopores and macropores, which is suitable for catalysis, adsorption, energy storage and other fields. The present invention adopts natural and renewable rosin resources to synthesize rosin acyl amino acids as soft templates, which are environmentally friendly and non-irritating to the human body; the carbon source and nitrogen source used are aminophenols with the advantages of low cost and wide sources. The self-assembled structure of the soft template of the present invention is easily manipulated by using a good / poor solvent system, and the polymerizer can be directly added without separation to achieve a one-step phenolic condensation reaction. The operation is simple, the conditions are mild, the preparation process is short, and it is suitable for large-scale production and industrial promotion.

Description

Technical Field

[0001] The present invention belongs to the field of functional porous materials, and in particular relates to a method for preparing a nitrogen and phosphorus co-doped carbon nanotube material with a hierarchical pore structure. Background Art

[0002] Hollow structured carbon nanomaterials, especially one-dimensional carbon nanotubes, are favored by researchers due to their unique structure and excellent physical and chemical properties (Tabassum H, Mahmood A, Zhu B, et al. Recent advances inconfining metal-based nanoparticles into carbon nanotubes for electrochemicalenergy conversion and storage devices[J]. Energy&Environmental Science, 2019,12(10): 2924-2956. De Volder MFL, Tawfick SH, Baughman RH, et al. Carbonnanotubes: present and future commercial applications[J]. science, 2013, 339(6119): 535-539.).Many classic methods, including arc method (Truus K, Volobujeva O, Kaupmees R,et al. Recent advances of carbon nanotubes synthesis by the electric arctechnique using atomized platinum-group metal catalysts[J]. Materials Scienceand Engineering: B, 2024, 300: 117121.), spray pyrolysis (Annu A, Bhattacharya B,Singh PK, et al. Carbon nanotube using spray pyrolysis: Recent scenario[J].Journal of Alloys and Compounds, 2017, 691: 970-982.) and chemical vapor deposition (Chen Y,Zhang J. Chemical vapor deposition growth of single-walled carbon nanotubeswith controlled structures for nanodevice applications[J]. Accounts ofchemical research, 2014, 47(8): 2273-2281.), have been successfully applied to the preparation of carbon nanotubes. Related research has greatly promoted the development of this field, but it still faces problems such as limited scale, high energy consumption, and expensive equipment. Furthermore, the aforementioned methods synthesize graphitized carbon nanotubes, which are mostly inert and require surface modification for application in specific fields. Furthermore, the pore structure of graphitized carbon nanotubes is underdeveloped, and even after activation, the specific surface area is very low, which greatly limits the expansion of their application areas. To address these issues, wet chemical synthesis of non-graphitized carbon nanotubes has been intensively studied.

[0003] Template method is an effective means of wet chemical synthesis of one-dimensional tubular carbon nanomaterials, mainly including hard template, self-template and soft template technology routes. Liu et al. (Liu F, Chuan X, Zhao Y. Hierarchical hollow tubularfibrous brucite-templated carbons obtained by KOH activation forsupercapacitors[J]. RSC advances, 2023, 13(10): 6606-6618.) used natural mineral fiber brucite as a hard template, glucose as a carbon source, and KOH as a chemical activator. After acid removal of the template, one-dimensional carbon nanotube materials with hierarchical pore structure were prepared. The use of KOH significantly increased the specific surface area of ​​the material (625 m 2 / g), forming a hierarchical pore structure with coexisting micro-, meso-, and macropores, resulting in a high specific capacitance (197 F / g) at 1 A / g. Xu et al. (Xu Z, Lu D, Ma L, et al. Hierarchically ordered carbon tube-sheet superstructure via template-directed self-assembly of polyimide[J]. Chemical Engineering Journal, 2019, 364: 201-207.) synthesized carbon nanotubes with surface nanosheet arrays using MoO3 nanorods as templates and polyimide (PI) as a carbon source. The study found that even a large number of MoO3 nanorods can guide the assembly of PI in solution into vertically aligned nanosheet arrays with a periodic structure. After template removal (ammonia etching) and thermal carbonization, these nanosheets can be converted into nitrogen-doped porous nanotube-sheet superstructures. While the hard template method can produce high-quality carbon nanotube materials, it requires the additional step of removing the template, which is often environmentally unfriendly. Wang et al. (Wang JG, Liu H, Zhang X, et al. Green synthesis of hierarchically porous carbon nanotubes as advanced materials for high-efficient energy storage[J]. Small, 2018, 14(13):1703950.) used manganese dioxide nanowires as a self-template to initiate the formation of polypyrrole-aniline conjugated polymers, which can be directly converted into nitrogen-doped carbon nanotube materials with hierarchical porous structures. The study showed that MnO2 is a good self-sacrificial oxidation template (MnO2 / Mn 2+ The chemical potential is 1.23 V), which can initiate the polymerization of pyrrole and aniline, and the MnO2 core will dissolve to form Mn 2+ The solution was then reacted to form a hollow structure conjugated polymer of polypyrrole-aniline. The obtained material had a core strength of 1419 m 2 / g high specific surface area and a hierarchical pore structure with coexisting micropores, mesopores, and macropores make this material an excellent electrode / host material for high-performance supercapacitors and lithium-sulfur batteries. Zhang et al. (Zhang LM, Sui XL, Zhao L, et al. Nitrogen-doped carbon nanotubes for high-performance platinum-based catalysts in methanol oxidation reaction[J]. Carbon, 2016, 108: 561-567.) prepared nitrogen-doped carbon nanotubes using a fibrous complex of methyl orange and the oxidant FeCl3 as a reactive self-sacrificial template to guide the growth of polypyrrole on its surface and promote its assembly into hollow nanotube structures. Zhao et al. (Zhao L, SuiX L, Zhou QY, et al. 1D N-doped hierarchically porous hollow carbon tubes derived from a supramolecular template as metal-free electrocatalysts for a highly efficient oxygen reduction reaction[J]. Journal of Materials ChemistryA, 2018, 6(15): 6212-6219.) used a supramolecular polymer prepared by the reaction of melamine and cyanuric acid as a self-template and nitrogen source, and glucose as a carbon source to prepare one-dimensional nitrogen-doped hollow carbon tubes with a hierarchical micro / mesoporous structure. The material has a high specific surface area, a well-organized hierarchical pore system, and a proliferation of catalytic active sites, resulting in excellent ORR electrocatalytic activity. Li et al. (Li H, Zuo P, Qu S, et al. Hybrid hierarchically porous carbon microntubes for trace cadmium and lead ions electrochemical detection[J]. Applied Surface Science, 2023, 615: 156426.) first formed a melamine-trithiocyanuric acid supramolecular polymer by supramolecular self-assembly and evaporation-induced drying. They then used this polymer as a self-template to mix with oxidized asphaltene and carbonize it to synthesize carbon microtubes with rich nitrogen and sulfur functional groups and a hierarchical porous structure. The resulting material was used to detect trace amounts of Cd 2+ and Pb 2+It can perform single and simultaneous detection with high sensitivity and detection limit, and has achieved satisfactory recovery rate when applied to actual water samples. Although the use of self-sacrificial template method can avoid the post-processing means of removing the template agent, it often requires the careful synthesis of the nanostructure of the self-sacrificial template in advance, and the synthesis process is still cumbersome. Yang et al. (Yang W, Liu X, Yue X, et al. Bamboo-like carbon nanotube / Fe3C nanoparticle hybrids and their highly efficient catalysis for oxygen reduction[J]. Journal of the American Chemical Society, 2015, 137(4): 1436-1439.) proposed a one-step soft template induction strategy to control the synthesis of bamboo-like carbon nanotubes by high-temperature annealing of a mixture of Pluronic P123 (P123), melamine and Fe(NO3)3. P123 can only form a linear structure in the presence of Fe(NO3)2 and melamine. Without the synthesis of P123, only nanoshell structures can be generated. Using only P123 and Fe(NO3)2 or P123 and melamine can only produce porous morphologies. The resulting carbon nanotube materials are highly active and stable ORR catalysts in both alkaline and acidic solutions. As can be seen from the above, the soft template method does not require the pre-synthesis of nanomaterial precursors, and can be decomposed and removed during the calcination process. It can effectively solve the problems existing in the hard template and self-template methods, and thus has better industrial prospects. However, the soft template agents reported so far still have the problems of being expensive and difficult to manipulate. There is an urgent need to develop new soft template agents to guide the synthesis of new carbon nanotubes. Summary of the Invention

[0004] The present invention addresses the complex and inefficient preparation methods for one-dimensional carbon nanotubes, the difficulty in regulating the one-dimensional morphology, surface properties, and pore structure of the carbon materials, and the difficulty in large-scale industrialization. By providing a method for preparing nitrogen- and phosphorus-co-doped carbon nanotubes with a hierarchical pore structure, the present invention utilizes rosin-based acylamino acids synthesized from a natural, renewable resource called rosin as a soft template, resulting in an environmentally friendly and non-irritating process. The carbon and nitrogen sources used are aminophenols, which have the advantages of low cost and wide availability. The synthesis method is simple to operate and has a short preparation process, making it suitable for large-scale production and industrialization.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for preparing a nitrogen-phosphorus co-doped carbon nanotube material with a hierarchical pore structure, comprising the following steps:

[0007] S1, mixing a soft template and a carbon / nitrogen source and dissolving them in a mixed solvent system to obtain a self-assembled structure;

[0008] Wherein, the soft template is rosin acyl amino acid, and the carbon / nitrogen source is aminophenol;

[0009] S2, adding a polymerizing agent to the solution system obtained in S1 to react to obtain a phenolic resin, and calcining the phenolic resin to obtain a nitrogen-doped carbon material;

[0010] S3. Mixing the nitrogen-doped carbon material obtained in S2 with an activator and calcining again to obtain a hierarchical porous nitrogen and phosphorus co-doped carbon nanotube material.

[0011] Furthermore, the rosin acyl amino acid described in S1 is N-dehydrorosin acyl-L-phenylalanine (C da -L-Phe), N-dehydroabietoylglycine (C da Gly), N-dehydroabietoyl-L-alanine (C da -L-Ala), N-dehydroabietoyl-L-phenylglycine (C da -L-Phg) and N-dehydroabietoyl-L-tyrosine (C da -L-Tyr) at least one.

[0012] Furthermore, the preparation method of the rosin acyl amino acid comprises: reacting dehydroabietic acid with oxalyl chloride to obtain dehydroabietic acid chloride, simultaneously adding the dehydroabietic acid chloride acetone solution and sodium hydroxide solution dropwise to an acetone solution of the amino acid with stirring, adjusting the pH to 1-2, filtering the precipitated solid, drying, and purifying the solid to obtain the amino acid. The amino acid is any one of L-phenylalanine, glycine, L-alanine, L-phenylglycine, and L-tyrosine, and the molar ratio of dehydroabietic acid chloride to the amino acid is 1:2.

[0013] Furthermore, the aminophenol described in S1 is at least one of 2-aminophenol, 3-aminophenol, and 4-aminophenol.

[0014] Furthermore, the mass ratio of rosin acyl amino acid to aminophenol in S1 is 1:(2-10).

[0015] Furthermore, the mixed solvent system in S1 consists of a good solvent and a poor solvent, the good solvent is at least one of methanol, ethanol, isopropanol and acetone, and the poor solvent is water, and the volume ratio of the good solvent and the poor solvent is 1:(5-20).

[0016] Furthermore, the polymerization agent in S2 is at least one of formaldehyde, glyoxal, and terephthalaldehyde; and the mass ratio of aminophenol to the polymerization agent is 1:(0.1-1).

[0017] Furthermore, the activator in S3 is at least one of phosphoric acid, pyrophosphoric acid, and potassium hydrogen phosphate; and the mass ratio of the nitrogen-doped carbon material to the activator is 1:(2-8).

[0018] Furthermore, the calcination temperature in S2 and S3 is both 600-1000° C., and the calcination time is both 2-8 h.

[0019] The beneficial effects of the present invention are:

[0020] 1. The present invention uses natural and renewable rosin resources to synthesize the soft template (rosin acyl amino acid), which is environmentally friendly and non-irritating to the human body. The carbon and nitrogen sources used are aminophenols, which have the advantages of low cost and wide availability.

[0021] 2. The self-assembled structure of the soft template of the present invention is easily manipulated using a good / bad solvent system. The polymerizer can be directly added without separation to achieve a one-step phenolic polycondensation reaction. The operation is simple, the conditions are mild, the preparation process is short, and it is suitable for large-scale production and industrial promotion.

[0022] 3. The carbon nanotubes prepared by this invention are highly dispersible and nanoscale, successfully achieving surface nitrogen and phosphorus co-doping to form abundant active sites. The resulting material has a high specific surface area and a porous structure with a coexistence of micropores, mesopores, and macropores, making it suitable for applications in catalysis, adsorption, energy storage, and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 SEM images of nitrogen-doped carbon materials prepared using different rosinyl amino acids as templates: N-dehydrorosinyl-L-phenylalanine (A—Example 1), N-dehydrorosinyl-glycine (B—Example 2), N-dehydrorosinyl-L-alanine (C—Example 3), N-dehydrorosinyl-L-phenylglycine (D—Example 4), N-dehydrorosinyl-L-tyrosine (E—Example 5), and no template added (F—Example 6).

[0024] Figure 2 SEM images of nitrogen-doped carbon materials prepared with different addition amounts of N-dehydroabietoyl-L-phenylalanine: 0.010 g (A—Example 7), 0.020 g (B—Example 8), 0.035 g (C—Example 9), 0.070 g (D—Example 10), 0.100 g (E—Example 1), and 0.200 g (F—Example 11).

[0025] Figure 3SEM images of Example 1 (A and B), Example 12 (C and D), Example 6 (E and F), Example 13 (G and H), Example 14 (I and J) and Example 15 (K and L); TEM image of Example 1 (M, N and O) and elemental mapping of Example 1 (P, Q, R, S and T): C (yellow), N (red), O (purple), P (green).

[0026] Figure 4 N2 adsorption-desorption isotherms (A), HK pore size distribution (B), DFT pore size distribution (C), micropore range distribution (D), mesopore and macropore range distribution (E) of Example 1 (a), Example 12 (b), Example 6 (c), Example 13 (d), Example 14 (e) and Example 15 (f). DETAILED DESCRIPTION

[0027] To make the objects, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be described clearly and completely below in conjunction with the examples. Where specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or the conditions recommended by the manufacturer. Where the manufacturer of the reagents or instruments is not specified, all are commercially available conventional products.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art in the art. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0029] The synthesis method of the raw material rosin acyl amino acid is specifically as follows:

[0030] 9 g of dehydroabietic acid was dissolved in dichloromethane, and 5.49 g of oxalyl chloride was added dropwise, followed by stirring at room temperature for 4 h. After the reaction was completed, the excess solvent was removed by rotary evaporation to obtain dehydroabietic acid chloride. A certain amount of L-phenylalanine was added to a mixed solution of acetone and water, and the pH value of L-phenylalanine was adjusted to 10 with an aqueous sodium hydroxide solution. Then, 0.5 times the molar amount of dehydroabietic acid chloride acetone solution and an aqueous sodium hydroxide solution were simultaneously added to the solution. After the addition was complete, stirring was continued at room temperature for 3 h. After the reaction was completed, the pH value was adjusted to 1-2 with a 6 M hydrochloric acid solution to precipitate a white solid. After filtration and drying, a crude N-dehydroabietic acid-L-phenylalanine product was obtained. Finally, it was purified by recrystallization (acetic acid and water) to obtain N-dehydroabietic acid-L-phenylalanine (C da -L-Phe).

[0031] Using the same method, N-dehydroabietoylglycine (C da Gly), N-dehydroabietoyl-L-alanine (C da -L-Ala), N-dehydroabietoyl-L-phenylglycine (C da -L-Phg) and N-dehydroabietoyl-L-tyrosine (C da -L-Tyr). During use, the rosin acyl amino acid is converted into rosin acyl amino acid sodium salt by reacting with sodium hydroxide.

[0032] The reaction process is as follows:

[0033]

[0034] Example 1

[0035] 1. Dissolve 0.1 g of N-dehydroabietoyl-L-phenylalanine and 0.2 g of 3-aminophenol in 14 mL of anhydrous methanol. Add 108.5 mL of deionized water at 333 K and stir at 1000 rpm for 40 min.

[0036] 2. Add 0.12 mL of formaldehyde solution (37%) to the resulting solution. After reacting for 2 h, filter and repeatedly wash with deionized water and ethanol. Dry under vacuum at 313 K to obtain a yellow phenolic resin. The obtained phenolic resin is placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under N2 atmosphere to obtain a nitrogen-doped carbon material.

[0037] like Figure 1 The SEM characterization in A shows that the obtained nitrogen-doped carbon material has a nanotube-like morphology.

[0038] 3. The obtained nitrogen-doped carbon material was mixed with phosphoric acid (85%) at a mass ratio of 1:4. After drying, the mixture was placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under a nitrogen atmosphere to obtain a nitrogen- and phosphorus-co-doped carbon material.

[0039] like Figure 3 As shown in SEM images of A and B, the carbon material obtained in this example can still maintain a nanotube morphology after activation with phosphoric acid.

[0040] Example 2

[0041] 1. Dissolve 0.1 g of N-dehydroabietoylglycine and 0.2 g of 3-aminophenol in 14 mL of anhydrous methanol. Add 108.5 mL of deionized water at 333 K and stir at 1000 rpm for 40 min.

[0042] 2. Add 0.12 mL of formaldehyde solution (37%) to the resulting solution. After reacting for 2 h, filter and repeatedly wash with deionized water and ethanol. Dry under vacuum at 313 K to obtain a yellow phenolic resin. The obtained phenolic resin is placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under N2 atmosphere to obtain a nitrogen-doped carbon material.

[0043] like Figure 1 From the SEM characterization in B, it can be seen that the obtained nitrogen-doped carbon material has a structure in which nanospheres and nanotubes coexist.

[0044] 3. The obtained nitrogen-doped carbon material was mixed with phosphoric acid (85%) at a mass ratio of 1:4. After drying, the mixture was placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under a nitrogen atmosphere to obtain a nitrogen- and phosphorus-co-doped carbon material.

[0045] Example 3

[0046] 1. Dissolve 0.1 g of N-dehydroabietoyl-L-alanine and 0.2 g of 3-aminophenol in 14 mL of anhydrous methanol. Add 108.5 mL of deionized water at 333 K and stir at 1000 rpm for 40 min.

[0047] 2. Add 0.12 mL of formaldehyde solution (37%) to the resulting solution. After reacting for 2 h, filter and repeatedly wash with deionized water and ethanol. Dry under vacuum at 313 K to obtain a yellow phenolic resin. The obtained phenolic resin is placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under N2 atmosphere to obtain a nitrogen-doped carbon material.

[0048] like Figure 1 SEM characterization in C shows that the obtained nitrogen-doped carbon material has a structure in which nanospheres and nanosheets coexist.

[0049] 3. The obtained nitrogen-doped carbon material was mixed with phosphoric acid (85%) at a mass ratio of 1:4. After drying, the mixture was placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under a nitrogen atmosphere to obtain a nitrogen- and phosphorus-co-doped carbon material.

[0050] Example 4

[0051] 1. Dissolve 0.1 g of N-dehydroabietoyl-L-phenylglycine and 0.2 g of 3-aminophenol in 14 mL of anhydrous methanol. Add 108.5 mL of deionized water at 333 K and stir at 1000 rpm for 40 min.

[0052] 2. Add 0.12 mL of formaldehyde solution (37%) to the resulting solution. After reacting for 2 h, filter and repeatedly wash with deionized water and ethanol. Dry under vacuum at 313 K to obtain a yellow phenolic resin. The obtained phenolic resin is placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under N2 atmosphere to obtain a nitrogen-doped carbon material.

[0053] like Figure 1 SEM characterization in D shows that the obtained nitrogen-doped carbon material has a nanosheet morphology.

[0054] 3. The obtained nitrogen-doped carbon material was mixed with phosphoric acid (85%) at a mass ratio of 1:4. After drying, the mixture was placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under a nitrogen atmosphere to obtain a nitrogen- and phosphorus-co-doped carbon material.

[0055] Example 5

[0056] 1. Dissolve 0.1 g of N-dehydroabietoyl-L-tyrosine and 0.2 g of 3-aminophenol in 14 mL of anhydrous methanol. Add 108.5 mL of deionized water at 333 K and stir at 1000 rpm for 40 min.

[0057] 2. Add 0.12 mL of formaldehyde solution (37%) to the resulting solution. After reacting for 2 h, filter and repeatedly wash with deionized water and ethanol. Dry under vacuum at 313 K to obtain a yellow phenolic resin. The obtained phenolic resin is placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under N2 atmosphere to obtain a nitrogen-doped carbon material.

[0058] like Figure 1 From the SEM characterization in E, it can be seen that the obtained nitrogen-doped carbon material has a nano-spherical morphology.

[0059] 3. The obtained nitrogen-doped carbon material was mixed with phosphoric acid (85%) at a mass ratio of 1:4. After drying, the mixture was placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under a nitrogen atmosphere to obtain a nitrogen- and phosphorus-co-doped carbon material.

[0060] Example 6 (control group without template in Example 1)

[0061] 1. Without adding any template, dissolve 0.2 g of 3-aminophenol in 14 mL of anhydrous methanol, add 108.5 mL of deionized water at 333 K, and stir at 1000 rpm for 40 min.

[0062] 2. Add 0.12 mL of formaldehyde solution (37%) to the resulting solution. After reacting for 2 h, filter and repeatedly wash with deionized water and ethanol. Dry under vacuum at 313 K to obtain a yellow phenolic resin. The obtained phenolic resin is placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under N2 atmosphere to obtain a nitrogen-doped carbon material.

[0063] like Figure 1 SEM characterization in F shows that the obtained nitrogen-doped carbon material has a nano-spherical morphology.

[0064] 3. The obtained nitrogen-doped carbon material was mixed with phosphoric acid (85%) at a mass ratio of 1:4. After drying, the mixture was placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under a nitrogen atmosphere to obtain a nitrogen- and phosphorus-co-doped carbon material.

[0065] Figure 1 SEM images of nitrogen-doped carbon materials prepared using different abietic acid amino acids as templates: N-dehydroabietic acid-L-phenylalanine (A), N-dehydroabietic acid-glycine (B), N-dehydroabietic acid-L-alanine (C), N-dehydroabietic acid-L-phenylglycine (D), N-dehydroabietic acid-L-tyrosine (E), and no template (F). N-dehydroabietic acid-L-phenylalanine is crucial for the formation of the tubular morphology, likely due to its ability to form rod-like aggregates in solution through interactions with 3-aminophenol (hydrogen bonding, hydrophilic and hydrophobic interactions, or electrostatic interactions).

[0066] Example 7

[0067] 1. Dissolve 0.01 g of N-dehydroabietoyl-L-phenylalanine and 0.2 g of 3-aminophenol in 14 mL of anhydrous methanol. Add 108.5 mL of deionized water at 333 K and stir at 1000 rpm for 40 min.

[0068] 2. Add 0.12 mL of formaldehyde solution (37%) to the resulting solution. After reacting for 2 h, filter and repeatedly wash with deionized water and ethanol. Dry under vacuum at 313 K to obtain a yellow phenolic resin. The obtained phenolic resin is placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under N2 atmosphere to obtain a nitrogen-doped carbon material.

[0069] like Figure 2 The SEM characterization in A shows that the obtained nitrogen-doped carbon material has a nano-spherical morphology.

[0070] 3. The obtained nitrogen-doped carbon material was mixed with phosphoric acid (85%) at a mass ratio of 1:4. After drying, the mixture was placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under a nitrogen atmosphere to obtain a nitrogen- and phosphorus-co-doped carbon material.

[0071] Example 8

[0072] 1. Dissolve 0.02 g of N-dehydroabietoyl-L-phenylalanine and 0.2 g of 3-aminophenol in 14 mL of anhydrous methanol. Add 108.5 mL of deionized water at 333 K and stir at 1000 rpm for 40 min.

[0073] 2. Add 0.12 mL of formaldehyde solution (37%) to the resulting solution. After reacting for 2 h, filter and repeatedly wash with deionized water and ethanol. Dry under vacuum at 313 K to obtain a yellow phenolic resin. The obtained phenolic resin is placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under N2 atmosphere to obtain a nitrogen-doped carbon material.

[0074] like Figure 2 From the SEM characterization in B, it can be seen that the obtained nitrogen-doped carbon material has a structure in which nanospheres and nanotubes coexist.

[0075] 3. The obtained nitrogen-doped carbon material was mixed with phosphoric acid (85%) at a mass ratio of 1:4. After drying, the mixture was placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under a nitrogen atmosphere to obtain a nitrogen- and phosphorus-co-doped carbon material.

[0076] Example 9

[0077] 1. Dissolve 0.035 g of N-dehydroabietoyl-L-phenylalanine and 0.2 g of 3-aminophenol in 14 mL of anhydrous methanol. Add 108.5 mL of deionized water at 333 K and stir at 1000 rpm for 40 min.

[0078] 2. Add 0.12 mL of formaldehyde solution (37%) to the resulting solution. After reacting for 2 h, filter and repeatedly wash with deionized water and ethanol. Dry under vacuum at 313 K to obtain a yellow phenolic resin. The obtained phenolic resin is placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under N2 atmosphere to obtain a nitrogen-doped carbon material.

[0079] like Figure 2 SEM characterization in C shows that the obtained nitrogen-doped carbon material has a structure in which nanospheres and nanotubes coexist.

[0080] 3. The obtained nitrogen-doped carbon material was mixed with phosphoric acid (85%) at a mass ratio of 1:4. After drying, the mixture was placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under a nitrogen atmosphere to obtain a nitrogen- and phosphorus-co-doped carbon material.

[0081] Example 10

[0082] 1. Dissolve 0.07 g of N-dehydroabietoyl-L-phenylalanine and 0.2 g of 3-aminophenol in 14 mL of anhydrous methanol. Add 108.5 mL of deionized water at 333 K and stir at 1000 rpm for 40 min.

[0083] 2. Add 0.12 mL of formaldehyde solution (37%) to the resulting solution. After reacting for 2 h, filter and repeatedly wash with deionized water and ethanol. Dry under vacuum at 313 K to obtain a yellow phenolic resin. The obtained phenolic resin is placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under N2 atmosphere to obtain a nitrogen-doped carbon material.

[0084] like Figure 2 SEM characterization in D shows that the obtained nitrogen-doped carbon material has a nanotube-like morphology.

[0085] 3. The obtained nitrogen-doped carbon material was mixed with phosphoric acid (85%) at a mass ratio of 1:4. After drying, the mixture was placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under a nitrogen atmosphere to obtain a nitrogen- and phosphorus-co-doped carbon material.

[0086] Example 11

[0087] 1. Dissolve 0.2 g of N-dehydroabietoyl-L-phenylalanine and 0.2 g of 3-aminophenol in 14 mL of anhydrous methanol. Add 108.5 mL of deionized water at 333 K and stir at 1000 rpm for 40 min.

[0088] 2. Add 0.12 mL of formaldehyde solution (37%) to the resulting solution. After reacting for 2 h, filter and repeatedly wash with deionized water and ethanol. Dry under vacuum at 313 K to obtain a yellow phenolic resin. The obtained phenolic resin is placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under N2 atmosphere to obtain a nitrogen-doped carbon material.

[0089] like Figure 2 SEM characterization in F shows that the obtained nitrogen-doped carbon material has a nanotube-like morphology.

[0090] 3. The obtained nitrogen-doped carbon material was mixed with phosphoric acid (85%) at a mass ratio of 1:4. After drying, the mixture was placed in a tube furnace and calcined at 1173 K for 4 h (heating rate of 3 K / min) under a nitrogen atmosphere to obtain a nitrogen- and phosphorus-co-doped carbon material.

[0091] Figure 2 SEM images of nitrogen-doped carbon materials prepared with different N-dehydroabietoyl-L-phenylalanine loadings: 0.010 g (A), 0.020 g (B), 0.035 g (C), 0.070 g (D), 0.100 g (E), and 0.200 g (F). When the N-dehydroabietoyl-L-phenylalanine loading is 0.010 g, the carbon material exhibits a predominantly spherical morphology. When the loading increases to 0.020 g and 0.035 g, the carbon material exhibits a mixed morphology of spherical and tubular structures. When the loading increases to 0.070 g, the carbon material exhibits a predominantly tubular morphology. As the loading increases, the diameter of the carbon nanotubes decreases. This may be due to the tendency of 3-aminophenol to accumulate on a small amount of template. As the loading increases, 3-aminophenol can disperse onto more template, resulting in a decrease in the diameter of the carbon nanotubes. When the addition amount increases to 0.100 g, the morphology of the carbon material is mainly tubular, and the diameter of the carbon nanotubes is further reduced. When the addition amount is 0.200 g ( Figure 2 F) The carbon material also has a tubular morphology, but the carbon nanotubes are clearly aggregated. This may be due to the accumulation of excess N-dehydroabietoyl-L-phenylalanine in the alcohol-water solution, which leads to the aggregation of the carbon nanotubes.

[0092] Example 12 (Unactivated Control Group of Example 1)

[0093] That is, the nitrogen-doped carbon material obtained in step 2 of Example 1.

[0094] Example 13 (Unactivated Control Group of Example 6)

[0095] That is, the nitrogen-doped carbon material obtained in step 2 of Example 6.

[0096] Example 14 (Iron Activation Group of Example 1)

[0097] Refer to the step parameters of Example 1, except that the activator phosphoric acid in step 3 is replaced by an equal mass of iron activator - FeCl3.

[0098] Example 15 (Zinc Activation Group of Example 1)

[0099] Refer to the step parameters of Example 1, except that the activator phosphoric acid in step 3 is replaced by an equal mass of zinc activator - ZnCl2.

[0100] Table 1 Pore structures of different carbon materials

[0101]

[0102] Figure 3 The following are SEM images of Example 1 (A and B, activated with template phosphoric acid), Example 12 (C and D, activated with template but not activated), Example 6 (E and F, activated with no template phosphoric acid), Example 13 (G and H, activated with no template but not activated), Example 14 (I and J, activated with template iron), and Example 15 (K and L, activated with template zinc); TEM image of Example 1 (M, N, and O) and elemental mapping of Example 1 (P, Q, R, S, and T): C (yellow), N (red), O (purple), P (green). Figure 3 SEM characterization in I~L shows that the material can still maintain the nanotube morphology after iron activation and zinc activation. Figure 3 TEM and elemental mapping characterizations in M~P show that the obtained material has a distinct nanotube morphology, nitrogen and phosphorus are uniformly doped in the carbon nanotube material, and the surface of the material also has abundant oxygen-containing groups.

[0103] Figure 4 A is the N2 adsorption-desorption isotherm of Example 1(a), Example 12(b), Example 6(c), Example 13(d), Example 14(e), and Example 15(f), Figure 4 B is the HK pore size distribution, Figure 4 C is the DFT pore size distribution, Figure 4 D is the micropore range distribution, Figure 4 E is the distribution of mesopores and macropores. Figure 4 As shown in Table 1, the obtained material has a high specific surface area of ​​2445.75m 2 / g, and a hierarchical pore structure with coexistence of micropores, mesopores and macropores, and the tube wall is non-graphitized.

[0104] The embodiments described above merely represent several preferred embodiments of the present invention. While the descriptions are relatively specific and detailed, they are not intended to limit the present invention. It should be noted that those skilled in the art will readily appreciate that the present invention is susceptible to various variations and modifications. Any modifications, equivalent substitutions, or improvements within the scope of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A method for preparing nitrogen and phosphorus co-doped carbon nanotube materials with a hierarchical pore structure, characterized in that: The steps include: S1, mixing a soft template and a carbon / nitrogen source and dissolving them in a mixed solvent system to obtain a self-assembled structure; Wherein, the soft template is rosin acyl amino acid, and the carbon / nitrogen source is aminophenol; S2, adding a polymerizing agent to the solution system obtained in S1 to react to obtain a phenolic resin, and calcining the phenolic resin to obtain a nitrogen-doped carbon material; S3, mixing the nitrogen-doped carbon material obtained in S2 with an activator, and calcining again to obtain a hierarchical porous nitrogen and phosphorus co-doped carbon nanotube material; The activator in S3 is at least one of phosphoric acid, pyrophosphoric acid, and potassium hydrogen phosphate.

2. The method for preparing nitrogen and phosphorus co-doped carbon nanotube material with hierarchical pore structure according to claim 1, characterized in that: S1 The rosin acyl amino acid is at least one of N-dehydrorosin acyl-L-phenylalanine, N-dehydrorosin acyl-glycine, N-dehydrorosin acyl-L-alanine, N-dehydrorosin acyl-L-phenylglycine and N-dehydrorosin acyl-L-tyrosine.

3. The method for preparing nitrogen and phosphorus co-doped carbon nanotube material with hierarchical pore structure according to claim 2, characterized in that: The preparation method of the rosin acyl amino acid comprises: reacting dehydroabietic acid with oxalyl chloride to obtain dehydroabietic acid chloride, simultaneously adding the dehydroabietic acid chloride acetone solution and a sodium hydroxide solution dropwise to an acetone solution of the amino acid with stirring, adjusting the pH value to 1-2, filtering the precipitated solid, drying, and purifying the solid to obtain the amino acid; the amino acid is any one of L-phenylalanine, glycine, L-alanine, L-phenylglycine, and L-tyrosine, and the molar ratio of dehydroabietic acid chloride to the amino acid is 1:

2.

4. The method for preparing nitrogen-phosphorus co-doped carbon nanotube material with hierarchical pore structure according to claim 1, characterized in that: The aminophenol described in S1 is at least one of 2-aminophenol, 3-aminophenol, and 4-aminophenol.

5. The method for preparing nitrogen and phosphorus co-doped carbon nanotube material with hierarchical pore structure according to claim 1, characterized in that: The mass ratio of rosin acyl amino acid to aminophenol in S1 is 1:(2-10).

6. The method for preparing nitrogen and phosphorus co-doped carbon nanotube material with hierarchical pore structure according to claim 1, characterized in that: S1 The mixed solvent system consists of a good solvent and a poor solvent, the good solvent is at least one of methanol, ethanol, isopropanol and acetone, and the poor solvent is water, and the volume ratio of the good solvent and the poor solvent is 1:(5-20).

7. The method for preparing nitrogen and phosphorus co-doped carbon nanotube material with hierarchical pore structure according to claim 1, characterized in that: The polymerization agent in S2 is at least one of formaldehyde, glyoxal, and terephthalaldehyde; and the mass ratio of aminophenol to the polymerization agent is 1:(0.1-1).

8. The method for preparing nitrogen-phosphorus co-doped carbon nanotube material with hierarchical pore structure according to claim 1, characterized in that: The mass ratio of the nitrogen-doped carbon material to the activator in S3 is 1:(2-8).

9. The method for preparing nitrogen and phosphorus co-doped carbon nanotube material with hierarchical pore structure according to claim 1, characterized in that: The calcination temperature in S2 and S3 is 600-1000° C., and the calcination time is 2-8 h.

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