Preparation method of nitrogen-doped hollow porous carbon nanospheres

Abstract

The application discloses a preparation method of nitrogen-doped hollow porous carbon nanospheres, and belongs to the field of functional porous materials. The rosin acyl amino acid synthesized by using natural renewable rosin as a precursor is used as a structure directing agent, and the utilization rate is high. Meanwhile, 3-amino phenol is used as a carbon source and a nitrogen source, and inorganic copper salt is used as a complex metal, and the method has the advantages of low cost and wide source. The preparation method is not only simple in operation, but also mild in reaction condition, significantly shortens the preparation process, provides an ideal way for large-scale production and industrial application, and is extremely valuable. The carbon nanospheres prepared by the application have clear cavity structure, high dispersity and uniform particle size, realize surface nitrogen doping, increase the surface active sites of the material, and have high specific surface area after activation, rich pore structure, and are suitable for the fields of catalysis, adsorption, energy storage and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of functional porous materials, and particularly relates to a preparation method of nitrogen-doped hollow porous carbon nanospheres. BACKGROUND

[0002] Carbonaceous materials have been widely used in adsorption, energy storage, and catalysis due to their large specific surface area, developed porosity, adjustable structure, and abundant surface active groups (Bai J, Huang J, Yu Q, et al. One-potsynthesis of self S-doped porous carbon for efficient CO2adsorption[J]. Fuel Processing Technology, 2023, 244: 107700. Kothandam G, Singh G, Guan X, et al. Recent Advances in Carbon‐Based Electrodes for Energy Storage and Conversion[J]. Advanced Science, 2023, 10(18): 2301045. Li P, Jiao Y, Ruan Y, et al. Revealing the role of double-layer microenvironments in pH-dependent oxygen reduction activity over metal-nitrogen-carbon catalysts[J]. Nature Communications, 2023, 14(1): 6936.). In particular, the various structures of carbon spheres, including hollow, core-shell, and solid structures, can endow carbonaceous materials with unique properties (Lan J, Wang B, Bo C, et al. Progress on fabrication and application of activated carbon sphere in recent decade[J]. Journal of Industrial and Engineering Chemistry, 2023, 120: 47-72.). Hollow nanostructures have many advantages in applications. For example, large specific surface area and open porous channels can provide abundant active sites for various electrochemical redox reactions.Thin permeable shell greatly reduces the fast transfer path of ions and electrons (Zhu J, Zhou H, Zhang C, et al. Dual active nitrogen doped hierarchical porous hollow carbon nanospheres as an oxygen reduction electrocatalyst for zinc-air batteries [J]. Nanoscale, 2017, 9(35): 13257-13263.), and the cavity provides additional volume to relieve strain and provide enough space for electrolyte penetration (Bin D S, Chi Z X, Li Y, et al. Controlling the compositional chemistry in single nanoparticles for functional hollow carbon nanospheres [J]. Journal of the American Chemical Society, 2017, 139(38): 13492-13498.).

[0003] One of the key steps to prepare hollow porous carbon spheres is to control the formation of hollow cores. In the past few decades, the use of hard templates with different structures is an effective method to prepare hollow porous carbon spheres with different structures. This method mainly includes the customization of spherical templates, the coating and carbonization of carbon sources on the surface of spherical templates, and the removal of templates. The synthesis strategy is relatively complex, and environmentally unfriendly reagents are often used in the template removal process (Liu R, Mahurin S M, Li C, et al. Dopamine as a carbon source: the controlled synthesis of hollow carbon spheres and yolk-structured carbon nanocomposites[J]. Angewandte Chemie-International Edition, 2011, 50(30): 6799. Du J, Zong S, Zhang Y, et al. Co-assembly strategy for uniform and tunable hollow carbon spheres with supercapacitor application[J]. Journal of colloid and interface science, 2020, 565: 245-253.).Different soft templates have also been applied to synthesize porous carbon spheres, such as Triton X-100 (Xu F, Tang Z, Huang S, et al. Facile synthesis of ultrahigh-surface-area hollow carbon nanospheres for enhanced adsorption and energy storage[J]. Nature communications, 2015, 6(1): 7221.), PMMA-b-PEA-b-PAA (Wang Z, Zhang S, Zhang L, et al. Hollow spherical carbonized polypyrrole / sulfur composite cathode materials for lithium / sulfur cells with long cycle life[J]. Journal of Power Sources, 2014, 248: 337-342.) and PS-b-P2VP-b-PEO (Li Y, Tan H, Salunkhe R R, et al. Hollow carbon nanospheres using an asymmetric triblock copolymer structure directing agent[J]. Chemical Communications, 2017, 53(1): 236-239.), etc. Compared with the hard template method, the soft template synthesis method is more simple in steps. On the one hand, the soft template can be directly pyrolyzed and removed during the carbonization process of the carbon source, and on the other hand, the soft template agent mainly utilizes the self-assembly characteristics of the template agent to form a spherical core in the reaction system, which can avoid the pre-customization step of the spherical template. However, since the soft template agent used is an amphiphilic compound, in order to obtain the self-assembly structure of the soft template agent, a relatively high concentration is often required, and after the synthesis of the hollow porous carbon sphere precursor, a large amount of template agent still remains in the reaction solvent, and the utilization rate of the soft template agent is low, but the soft template agent itself is expensive, which greatly limits the large-scale production of the synthesis of porous carbon spheres by the soft template method. At the same time, the self-assembly structure of the soft template agent is poor in stability, and the requirements for the control conditions during the synthesis process are high, which is not conducive to industrial application. SUMMARY

[0004] The present application aims at the problems of current hollow porous carbon nanospheres preparation method, such as complex process, high cost, difficult microstructure regulation, etc., and proposes a preparation method of nitrogen-doped hollow porous carbon nanospheres. The method uses rosin acyl amino acid as a structure directing agent, which is synthesized from natural renewable rosin, is low in price and harmless to human body. Meanwhile, 3-aminophenol is used as carbon source and nitrogen source, and inorganic copper salt is used as complex metal, which has the advantages of low cost and wide source. The synthesis method is simple in operation, short in preparation process, and is very suitable for large-scale production and industrialization.

[0005] To achieve the above purpose, the present application adopts the following technical solutions:

[0006] The present application provides a preparation method of nitrogen-doped hollow porous carbon nanospheres, comprising the following steps:

[0007] S1, the structure directing agent, copper salt and aminophenol are mixed and dissolved in an alcohol solvent, and water is added and stirred to construct ternary complex colloidal nanospheres;

[0008] Among them, the structure directing agent is rosin acyl amino acid;

[0009] S2, a polymerization agent is added to the solution system obtained in S1, and a hollow carbon nanosphere precursor is obtained by reaction, and the hollow carbon nanosphere precursor is calcined to obtain a hollow porous carbon nanosphere;

[0010] S3, the hollow porous carbon nanospheres obtained in S2 are mixed with an activating agent and calcined again to obtain nitrogen-doped hollow porous carbon nanospheres.

[0011] Further, the rosin acyl amino acid in S1 is at least one of N-dehydroabietoyl-L-phenylalanine, N-dehydroabietoyl glycine, N-dehydroabietoyl-L-alanine, N-dehydroabietoyl-L-phenylglycine and N-dehydroabietoyl-L-tyrosine.

[0012] Further, the preparation method of the rosin acyl amino acid is as follows: dehydroabietic acid is reacted with oxalyl chloride to obtain dehydroabietoyl chloride, an acetone solution of the amino acid is added dropwise with stirring, and a sodium hydroxide solution is added dropwise with stirring, the pH value is adjusted to 1-2, and the solid is separated by suction filtration, dried and purified to obtain the rosin acyl amino acid; the amino acid is any one of L-phenylalanine, glycine, L-alanine, L-phenylglycine and L-tyrosine, and the molar ratio of dehydroabietoyl chloride to amino acid is 1:2.

[0013] Further, the copper salt in S1 is at least one of copper chloride, copper nitrate and copper acetate.

[0014] Further, the mass ratio of the rosin acyl amino acid, copper salt and aminophenol in S1 is 1:(3-7):(1-3).

[0015] Further, the alcohol solvent in S1 is at least one of methanol, ethanol, isopropanol and acetone; the volume ratio of the alcohol solvent to water is 1:(4-18).

[0016] Further, the polymerizing agent in S2 is at least one of formaldehyde, glyoxal and p-benzene dialdehyde; the mass ratio of the amino phenol to the polymerizing agent is 1:(0.1-1).

[0017] Further, the activating agent in S3 is at least one of ferric chloride, phosphoric acid and zinc chloride; the mass ratio of the hollow porous carbon nanosphere to the activating agent is 1:(4-8).

[0018] Further, the calcination temperature in S2 and S3 is 800-1000 DEG C, and the calcination time is 4-6 h.

[0019] The present application firstly proposes that rosin acyl amino acid is used as a structure directing agent, 3-amino phenol is used as a carbon source, copper ion is used as an induced complex metal, the three-component complex colloidal nanosphere is constructed as a template by dissolving in an alcohol solvent and using water to precipitate, and 3-amino phenol is polymerized by using a polymerizing agent. The 3-amino phenol at the interface of the ternary complex colloidal nanosphere and the solvent is preferentially polymerized, and more 3-amino phenol rapidly diffuses and copolymerizes from the inside of the complex colloidal to form a hollow structure. After calcination and pyrolysis, the rosin acyl amino acid is decomposed and removed, and finally the hollow porous carbon nanosphere is generated.

[0020] The present application has the following beneficial effects:

[0021] 1. The present application uses rosin acyl amino acid as a structure directing agent, which is synthesized by taking natural renewable rosin as a precursor, is low in price and harmless to human body. Meanwhile, 3-amino phenol is used as a carbon source and a nitrogen source, and inorganic copper salt is used as a complex metal, which has the advantages of low cost and wide source.

[0022] 2. In the process of the present application, due to the strong hydrophobicity of rosin acyl amino acid, the structure directing agent is completely precipitated when a poor solvent water is introduced into the reaction system, and is bridged by copper ion to form a complex colloidal nanosphere with 3-amino phenol, which greatly improves the utilization rate of the structure directing agent rosin acyl amino acid (close to 100%). Meanwhile, 3-amino phenol is both a carbon source and a self-template agent, which solves the instability of the self-assembled structure of the structure directing agent after the introduction of the carbon source.

[0023] 3、The operation steps of the present application are simple and easy to implement, only need to dissolve the abietinoyl amino acid, 3-aminophenol and copper salt in alcohol, and add water to form a self-assembly structure, due to the strong self-assembly ability of the abietinoyl amino acid, the water can be added at one time quickly, and the adding rate does not need to be controlled. At the same time, since the carbon source 3-aminophenol is also complexed in the colloidal nanospheres, the polymerization will preferentially occur on the interface, so the adding rate of the polymerization agent does not need to be strictly controlled, which lays a foundation for the industrial application of the present application.

[0024] 4、The carbon nanospheres prepared by the present application have a clear cavity structure, high dispersity and uniform particle size, realize surface nitrogen doping to increase the surface active sites of the material, and after activation, the material has high specific surface area and rich pore structure, and is suitable for catalysis, adsorption, energy storage and other fields. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Is the SEM image of carbon material prepared by using different abietinoyl amino acids as structure directing agents under the addition of CuCl2: N-dehydroabietinoyl-L-phenylalanine (A), N-dehydroabietinoyl glycine (B), N-dehydroabietinoyl-L-alanine (C), N-dehydroabietinoyl-L-phenylglycine (D), N-dehydroabietinoyl-L-tyrosine (E) and without adding template agent (F).

[0026] Figure 2 Is the SEM image of carbon material prepared by using N-dehydroabietinoyl-L-phenylalanine as structure directing agent under the addition of different metal salts: CuCl2 (A), FeCl3 (B), CoCl2 (C), NiCl2 (D), ZnCl2 (E) and without adding metal salt (F).

[0027] Figure 3 Is the SEM image of iron-activated nitrogen-doped hollow porous carbon nanospheres (A) and unactivated nitrogen-doped hollow carbon nanospheres (B).

[0028] Figure 4 Is the XPS image of nitrogen-doped hollow porous carbon nanospheres.

[0029] Figure 5 Is the TEM image of iron-activated nitrogen-doped hollow porous carbon nanospheres. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described clearly and completely below in combination with examples. If the specific conditions are not specified in the examples, conventional conditions or manufacturer's recommended conditions are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0032] The synthesis method of the raw material rosin acyl amino acid is specifically as follows:

[0033] 9 g of dehydroabietic acid was dissolved in dichloromethane, 5.49 g of oxalyl chloride was added dropwise, and then stirred 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 the L-phenylalanine was adjusted to 10 with a sodium hydroxide aqueous solution. Then, 0.5 times the molar amount of dehydroabietic acid chloride in L-phenylalanine was added dropwise to the solution, and the solution was continuously stirred at room temperature for 3 h after the dropwise addition was completed. After the reaction was completed, the pH value was adjusted to 1-2 with a 6 M hydrochloric acid solution, and white solids were precipitated. After filtration and drying, N-dehydroabietoyl-L-phenylalanine was obtained. Finally, recrystallization (acetic acid and water) was used for purification to obtain N-dehydroabietoyl-L-phenylalanine (C da -L-Phe).

[0034] Using the same method, L-phenylalanine was replaced by glycine, L-alanine, L-phenylglycine, and L-tyrosine, respectively, to obtain N-dehydroabietoyl glycine (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).

[0035] Example 1

[0036] 1. 0.1 g of N-dehydroabietoyl-L-phenylalanine, 0.2 g of 3-aminophenol, and 0.3 g of copper chloride were dissolved in 14 mL of anhydrous methanol, 108.5 mL of deionized water was added at 333 K, and stirred at 1000 rpm for 40 min.

[0037] 2. To the resulting solution system, 0.12 mL of formaldehyde solution (37%) was added, and after 2 h of reaction, the product was filtered and washed with deionized water and ethanol repeatedly, and then dried under vacuum at 313 K to obtain the hollow carbon nanospheres precursor. The obtained phenolic resin was placed in a tube furnace and calcined at 1173 K for 4 h under N2 atmosphere (the heating rate was 3 K / min) to obtain the hollow porous carbon nanospheres.

[0038] Example 2

[0039] Referring to the step parameters of Example 1, the difference is that N-dehydroabietyl-L-phenylalanine is replaced by equal mass of N-dehydroabietyl glycine.

[0040] Example 3

[0041] Referring to the step parameters of Example 1, the difference is that N-dehydroabietyl-L-phenylalanine is replaced by equal mass of N-dehydroabietyl-L-alanine.

[0042] Example 4

[0043] Referring to the step parameters of Example 1, the difference is that N-dehydroabietyl-L-phenylalanine is replaced by equal mass of N-dehydroabietyl-L-phenylglycine.

[0044] Example 5

[0045] Referring to the step parameters of Example 1, the difference is that N-dehydroabietyl-L-phenylalanine is replaced by equal mass of N-dehydroabietyl-L-tyrosine.

[0046] Example 6

[0047] Referring to the step parameters of Example 1, the difference is that no rosin amido acid is added.

[0048] Figure 1 SEM images of carbon materials prepared with different rosin amido acids as structure directing agents under the addition of CuCl2: N-dehydroabietyl-L-phenylalanine (A), N-dehydroabietyl glycine (B), N-dehydroabietyl-L-alanine (C), N-dehydroabietyl-L-phenylglycine (D), N-dehydroabietyl-L-tyrosine (E) and without template (F). As shown in A-E, the carbon materials prepared by adding different rosin amido acids have certain regular morphology, among which the carbon material prepared by adding N-dehydroabietyl-L-phenylalanine (A) has the best regular morphology. Figure 1 A-E, the carbon materials prepared by adding different rosin amido acids have certain regular morphology, among which the carbon material prepared by adding N-dehydroabietyl-L-phenylalanine (A) has the best regular morphology. Figure 1 A), N-dehydroabietyl-L-phenylglycine (D) and N-dehydroabietyl-L-tyrosine (E) have the best regular morphology. Figure 1 A), N-dehydroabietyl-L-phenylglycine (D) and N-dehydroabietyl-L-tyrosine (E) have the best regular morphology. Figure 1E) as the structure-directing agent is a uniformly dispersed hollow sphere; the carbon material with N-dehydroabietoylglycine as the structure-directing agent is spherical, but the size is uneven and the agglomeration is serious ( Figure 1 B); The carbon material with N-dehydroabietoyl-L-alanine as the structure-directing agent has a mixed morphology of spherical and tubular shapes ( Figure 1 C); while the carbon material without rosin acyl amino acid addition was irregular granular and agglomerated in large quantities ( Figure 1 F). Therefore, rosin acyl amino acids play an important role in the formation of hollow spherical structures, and the presence of benzene rings on the amino acids is more conducive to the formation of hollow spheres with stable structures and uniform shapes.

[0049] Example 7

[0050] Refer to the step parameters of Example 1, except that cupric chloride is replaced with ferric chloride of equal mass.

[0051] Example 8

[0052] Refer to the step parameters of Example 1, except that cupric chloride is replaced with an equal mass of cobalt chloride.

[0053] Example 9

[0054] Refer to the step parameters of Example 1, except that cupric chloride is replaced by an equal mass of nickel chloride.

[0055] Example 10

[0056] Refer to the step parameters of Example 1, except that cupric chloride is replaced with an equal mass of zinc chloride.

[0057] Example 11

[0058] The step parameters are the same as those in Example 1, except that no metal salt is added.

[0059] Figure 2 The following are SEM images of carbon materials prepared with N-dehydroabietoyl-L-phenylalanine as the structure-directing agent under the addition of different metal salts: CuCl2 (A), FeCl3 (B), CoCl2 (C), NiCl2 (D), ZnCl2 (E) and without metal salt (F). Figure 2 As shown in AF, for the carbon material without adding metal salt, its morphology is a single tubular ( Figure 2 F), when metal salts are introduced into the system, the morphology of the obtained carbon material changes. The carbon material with CuCl2 added is a single hollow sphere ( Figure 2 A); the carbon material with FeCl3 added is a mixture of spheres, rods and flakes ( Figure 2 B); the carbon material with added CoCl2 and NiCl2 is a mixture of spheres and rods (Figure 2 C and D); while the carbon material with ZnCl2 addition is a mixture of spheres and sheets (E). Figure 2 E). The above results show that the introduction of metal salts can change the original structure, and the introduction of CuCl2 is of great significance to the formation of hollow spherical structure.

[0060] Example 12

[0061] Referring to the parameters of step 1 of Example 1, an activation treatment step is added. The specific activation method is to mix the obtained hollow porous carbon nanospheres with FeCl3, and the mass ratio of hollow porous carbon nanospheres to FeCl3 is 1:4. The mixture is dried and then placed in a tube furnace, calcined at 1173 K under N2 atmosphere for 4 h (the heating rate is 3 K / min), and finally washed with 10% hydrochloric acid solution and then repeatedly washed with deionized water until neutral (pH = 7) to obtain nitrogen-doped hollow porous carbon nanospheres.

[0062] Figure 3 SEM images of iron-activated nitrogen-doped hollow porous carbon nanospheres (A) and unactivated nitrogen-doped hollow carbon nanospheres (B). As shown in Figure 3 It can be seen that the sample after activation still maintains a good hollow carbon nanosphere structure, and there are a large number of cracks on the surface of the sphere, indicating that it has a rich pore structure, which is due to the activation of FeCl3. N2-adsorption desorption detection shows that the specific surface area of the obtained material is 1137.18 m 2 / g, and the pore volume is 0.27 cm 3 / g, which again proves that the obtained hollow carbon material has a rich pore structure.

[0063] Figure 4 XPS image of nitrogen-doped hollow porous carbon nanospheres. As shown in Figure 4 It can be seen that the high-resolution XPS spectrum of N1s of the material can be divided into four characteristic peaks, which are pyridine nitrogen (397.31 eV), pyrrole nitrogen (398.66 eV), graphite nitrogen (400.83 eV) and quaternary ammonium nitrogen (401.60 eV), further proving that N in 3-aminophenol is successfully doped into the carbon material.

[0064] Figure 5 TEM image of iron-activated nitrogen-doped hollow porous carbon nanospheres. As shown in Figure 5 It can be seen that the prepared carbon nanospheres have a clear hollow structure, and a rich pore structure can be observed on the surface of the carbon shell, which again proves that the obtained material is a hollow porous carbon nanosphere.

[0065] The above described embodiments only express several preferred embodiments of the present application, which are described in a more specific and detailed manner, but are not used to limit the present application. It should be noted that the present application can also have various changes and modifications for those skilled in the art, and any modification, equivalent replacement, improvement, etc. made within the concept and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing nitrogen-doped hollow porous carbon nanospheres, characterized in that: The steps include: S1, dissolving a structure-directing agent, copper salt, and aminophenol in an alcohol solvent, adding water and stirring to construct ternary complex colloidal nanospheres; Wherein, the structure directing agent is rosin acyl amino acid; S2, adding a polymerizing agent to the solution system obtained in S1, reacting to obtain a hollow carbon nanosphere precursor, and calcining the hollow carbon nanosphere precursor to obtain hollow porous carbon nanospheres; Wherein, the polymerization agent is at least one of formaldehyde, glyoxal, and terephthalaldehyde; S3. Mix the hollow porous carbon nanospheres obtained in S2 with an activator, and calcine again to obtain nitrogen-doped hollow porous carbon nanospheres.

2. The method for preparing nitrogen-doped hollow porous carbon nanospheres according to claim 1, wherein: 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-doped hollow porous carbon nanospheres according to claim 2, wherein: 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-doped hollow porous carbon nanospheres according to claim 1, wherein: The copper salt in S1 is at least one of copper chloride, copper nitrate and copper acetate.

5. The method for preparing nitrogen-doped hollow porous carbon nanospheres according to claim 1, wherein: The mass ratio of rosin acyl amino acid, copper salt and aminophenol in S1 is 1:(3-7):(1-3).

6. The method for preparing nitrogen-doped hollow porous carbon nanospheres according to claim 1, characterized in that: The alcohol solvent in S1 is at least one of methanol, ethanol, and isopropanol; and the volume ratio of the alcohol solvent to water is 1:(4-18).

7. The method for preparing nitrogen-doped hollow porous carbon nanospheres according to claim 1, characterized in that: The mass ratio of aminophenol to polymerizing agent is 1:(0.1-1).

8. The method for preparing nitrogen-doped hollow porous carbon nanospheres according to claim 1, characterized in that: The activator in S3 is at least one of ferric chloride, phosphoric acid, and zinc chloride; the mass ratio of the hollow porous carbon nanospheres to the activator is 1:(4-8).

9. The method for preparing nitrogen-doped hollow porous carbon nanospheres according to claim 1, characterized in that: The calcination temperature in S2 and S3 is both 800-1000° C., and the calcination time is both 4-6 h.

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