Nitrogen-doped carbon aerogel as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of carbon aerogel, and particularly relates to nitrogen-doped carbon aerogel as well as a preparation method and application thereof. The preparation method comprises the following steps: (1) uniformly mixing a carbon source, a nitrogen source and a solvent to obtain nitrogen-doped gel; (2) aging the nitrogen-doped gel, and drying to obtain nitrogen-doped dry gel; and (3) carbonizing the nitrogen-doped dry gel to obtain the nitrogen-doped carbon aerogel. The preparation method is simple in process and low in cost, and the prepared nitrogen-doped carbon aerogel has a high specific surface area, a rich pore structure and good magnetic performance, and has a wide application prospect in the fields of environmental governance and energy storage. According to the invention, pollutants in wastewater can be efficiently adsorbed, and rapid separation and recovery can be realized under the action of an external magnetic field; in energy storage, the material shows excellent electrochemical performance as an electrode material of a supercapacitor.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon aerogels, and in particular relates to a nitrogen-doped carbon aerogel and a preparation method and application thereof. Background Art

[0002] Carbon aerogels, a material with high specific surface area, low density, good electrical conductivity, and thermal stability, are widely used in electrochemical energy storage, catalyst supports, adsorption materials, and other fields. However, the preparation of traditional carbon aerogels relies heavily on fossil fuels, which not only increases costs but also poses environmental risks. Therefore, finding sustainable and low-cost magnetic nanoparticles to prepare carbon aerogels has become a research priority.

[0003] CN115920790A discloses a method for preparing multifunctional nitrogen-doped carbon aerogels. The precursor is a double-network hydrogel formed by the self-assembly of a metal-organic framework gel and a helical collagen peptide. After drying, the hydrogel is pyrolyzed to produce a FeCo / Fe3O4 / NC nitrogen-doped carbon aerogel. However, this method is not environmentally friendly, and the wastewater generated can easily cause environmental pollution.

[0004] CN105152159A discloses a nitrogen-doped carbon aerogel and a preparation method thereof, comprising: (1) preparing a trihydroxypyridine solution, adding resorcinol, and after the solution is clarified, adding formaldehyde solution, stirring and adding potassium carbonate; (2) allowing the solution to stand to form an aerogel; (3) subjecting the aerogel to solvent exchange with acetone to obtain a trihydroxypyridine-resorcinol-formaldehyde gel; (4) placing the trihydroxypyridine-resorcinol-formaldehyde gel in a supercritical carbon dioxide extractor and subjecting it to supercritical carbon dioxide drying to obtain a xerogel; (5) placing the xerogel in a programmable temperature-controlled carbonization furnace and sintering and carbonizing it under inert gas protection to obtain a nitrogen-doped carbon aerogel. However, this method has high gel material preparation costs, poor performance reproducibility of pure biomass aerogels, and a single material function.

[0005] Therefore, the prior art still requires a method for preparing carbon aerogel with simple preparation process and reliable product quality. Summary of the Invention

[0006] The present invention aims to address the shortcomings of existing carbon aerogel preparation methods by obtaining a carbon aerogel with excellent physical and chemical properties through carbonization, thereby expanding the application field of carbon aerogels. The detailed technical solution of the present invention is described below.

[0007] The present invention provides a method for preparing nitrogen-doped carbon aerogel, which is characterized by comprising the following steps:

[0008] (1) uniformly mixing a carbon source, a nitrogen source, and a solvent to obtain a nitrogen-doped gel;

[0009] (2) aging the nitrogen-doped gel and then drying it to obtain a nitrogen-doped xerogel;

[0010] (3) The nitrogen-doped xerogel is carbonized to obtain nitrogen-doped carbon aerogel.

[0011] Preferably, in step (1), a cross-linking agent is further added, specifically, after the carbon source, nitrogen source and solvent are uniformly mixed, the cross-linking agent is added and stirred.

[0012] Preferably, the carbon source comprises at least one of phenolic resin, resorcinol, formaldehyde resin, glucose and sucrose.

[0013] Preferably, the nitrogen source includes at least one of urea, melamine and ethylenediamine.

[0014] Preferably, the cross-linking agent includes at least one of formaldehyde and glutaraldehyde.

[0015] Preferably, the aging in step (2) is carried out under an inert atmosphere, which is nitrogen or argon. The aging treatment time is 12 to 72 hours and the temperature is 20 to 80°C.

[0016] Preferably, the solvent includes at least one of ethanol and acetone.

[0017] Preferably, the temperature of the carbonization treatment in step (3) is 600-1000° C., and the time is 1-5 hours.

[0018] The present invention also protects a nitrogen-doped carbon aerogel prepared by the above-mentioned preparation method.

[0019] The present invention also protects the application of nitrogen-doped carbon aerogel in electrochemical energy storage, catalyst support, and adsorption material.

[0020] The first inventive point of the present invention is to introduce a nitrogen source into the production process, utilize in-situ nitrogen doping technology to obtain nitrogen-doped gel, and achieve uniform doping of nitrogen atoms into the carbon skeleton through controlled pyrolysis to form stable CN bonds, thereby avoiding structural damage caused by traditional post-treatment methods to enhance the physical and chemical properties of carbon aerogels, introduce nitrogen atoms to form electron donor sites, and enhance the adsorption activity of metal ions / gas molecules, making it suitable for catalysis or sensing scenarios.

[0021] The second inventive point of the present invention is that the nitrogen-doped carbon aerogel prepared by this method not only retains the original excellent properties of the carbon aerogel, but also gives the material better thermal insulation, flame retardant effects and other properties. It is suitable for supercapacitor electrode materials, lithium-ion battery negative electrode materials, electrocatalysis and adsorption of organic pollutants and other fields.

[0022] Therefore, the beneficial effects of the present invention are:

[0023] (1) The process of the present invention is simple, efficient and low-cost. The prepared nitrogen-doped carbon aerogel has a high specific surface area, rich pore structure and good conductivity, and exhibits excellent performance in the fields of supercapacitor electrode materials, lithium-ion battery negative electrode materials, electrocatalysis and adsorption of organic pollutants.

[0024] (2) The entire process of the present invention complies with the principles of green chemistry and helps promote sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Graph showing nitrogen content and specific surface area of nitrogen-doped carbon aerogel electrode materials in the examples. DETAILED DESCRIPTION

[0026] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0027] Example

[0028] Example 1

[0029] 1. Mix 10 g of resorcinol, 15 g of formaldehyde, 5 g of urea, and 100 mL of water, and stir at 60 ° C for 12 h to obtain a gel.

[0030] 2. The gel was aged at 60°C for 24 h and then freeze-dried to obtain a xerogel.

[0031] 3. Carbonize the dry gel at 800℃ for 3h under nitrogen atmosphere to obtain nitrogen-doped carbon aerogel.

[0032] The specific surface area of the nitrogen-doped carbon aerogel is 760 m 2 / g, the nitrogen content (XPS) is 8.2at%, the porosity is 91%, and the pore size distribution is 2-50nm.

[0033] Example 2

[0034] 1. Mix 20 g of glucose, 10 g of melamine, 80 mL of ethanol, and 5 mL of glutaraldehyde, and stir at 40°C for 8 h to obtain a gel.

[0035] 2. The gel was aged at 40 °C for 36 h and then subjected to supercritical drying to obtain a xerogel.

[0036] 3. Carbonize the dry gel at 900℃ for 2h under argon atmosphere to obtain nitrogen-doped carbon aerogel.

[0037] The specific surface area of the nitrogen-doped carbon aerogel is 810 m 2 / g, the nitrogen content (XPS) is 8.9at%, the porosity is 94%, and the pore size distribution is 2-50nm.

[0038] Example 3

[0039] 1. Mix 15 g of phenolic resin, 8 g of ethylenediamine, 50 mL of acetone, and 3 mL of formaldehyde, and stir at 50°C for 18 h to obtain a gel.

[0040] 2. The gel was aged at 50°C for 48 h and then freeze-dried to obtain a xerogel.

[0041] 3. Carbonize the dry gel at 700 °C for 4 h under a nitrogen atmosphere to obtain nitrogen-doped carbon aerogel.

[0042] The specific surface area of the nitrogen-doped carbon aerogel is 720 m 2 / g, the nitrogen content (XPS) is 7.8at%, the porosity is 89%, and the pore size distribution is 2-50nm.

[0043] Example 4

[0044] 1. Mix 12 g of phenol, 8 g of hexamethylenetetramine, 6 g of melamine, and 100 mL of deionized water, and stir at 70°C for 10 h to obtain a gel.

[0045] 2. The gel was aged at 70°C for 24 h and then freeze-dried to obtain a xerogel.

[0046] 3. Carbonize the dry gel at 850 °C for 2.5 h under nitrogen atmosphere to obtain nitrogen-doped carbon aerogel.

[0047] The specific surface area of the nitrogen-doped carbon aerogel is 700 m 2 / g, the nitrogen content (XPS) is 8.0at%, the porosity is 93%, and the pore size distribution is 2-50nm.

[0048] Example 5

[0049] 1. Mix 15 g chitosan, 10 g formaldehyde, 5 g urea and 80 mL 1% acetic acid aqueous solution, stir and react at 50°C for 15 h to obtain a gel.

[0050] 2. The gel was aged at 50°C for 36 h and then subjected to supercritical drying (CO2) to obtain a xerogel.

[0051] 3. Carbonize the dry gel at 750 °C for 3 h under argon atmosphere to obtain nitrogen-doped carbon aerogel.

[0052] The specific surface area of the nitrogen-doped carbon aerogel is 650 m 2 / g, nitrogen content (XPS) is 10.5at%, porosity is 90%, and pore size distribution is 2-50nm.

[0053] The relevant information and test performance data of the carbon aerogel composite material prepared above are shown in Table 1.

[0054] Table 1

[0055]

[0056] Figure 1 Graph 1 shows the nitrogen content and specific surface area of the nitrogen-doped carbon aerogel electrode material in the embodiment. The graph shows that the nitrogen content of the nitrogen-doped carbon aerogel material decreases first and then increases with increasing specific surface area, and has a relatively high nitrogen content.

[0057] The results show that the material has excellent physical and chemical properties, a high carbonization temperature (900°C), and a high specific surface area. Using biomass chitosan as the carbon source has a higher nitrogen content (10.5at%), but a slightly lower specific surface area.

[0058] These examples provide the effects of different raw material combinations and process parameters on the properties of nitrogen-doped carbon aerogels, and the preparation method can be optimized according to specific application requirements.

[0059] Based on the disclosure and teachings of the above description, those skilled in the art may also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and any modifications and variations of the invention should also fall within the scope of protection of the claims of the present invention. In addition, although certain specific terms are used in this description, these terms are for convenience of description only and do not constitute any limitation to the present invention.

Claims

1. A method for preparing nitrogen-doped carbon aerogel, characterized in that: The following steps are involved: (1) uniformly mixing a carbon source, a nitrogen source, and a solvent to obtain a nitrogen-doped gel; (2) aging the nitrogen-doped gel and then drying it to obtain a nitrogen-doped xerogel; (3) The nitrogen-doped xerogel is carbonized to obtain nitrogen-doped carbon aerogel.

2. The preparation method according to claim 1, characterized in that In step (1), a cross-linking agent is also added. Specifically, the carbon source, nitrogen source and solvent are mixed evenly, and then the cross-linking agent is added and stirred.

3. The preparation method according to claim 2, characterized in that The carbon source includes at least one of phenolic resin, resorcinol, formaldehyde resin, glucose and sucrose.

4. The preparation method according to claim 2, characterized in that The nitrogen source includes at least one of urea, melamine and ethylenediamine.

5. The preparation method according to claim 2, characterized in that The cross-linking agent includes at least one of formaldehyde and glutaraldehyde.

6. The preparation method according to claim 1, characterized in that In step (2), the aging is carried out under an inert atmosphere, which is nitrogen or argon. The aging treatment time is 12 to 72 hours and the temperature is 20 to 80°C.

7. The preparation method according to claim 1, characterized in that The solvent includes at least one of ethanol and acetone.

8. The preparation method according to claim 1, characterized in that The temperature of the carbonization treatment in step (3) is 600-1000° C., and the time is 1-5 hours.

9. A nitrogen-doped carbon aerogel, characterized in that It is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the nitrogen-doped carbon aerogel according to claim 9 in electrochemical energy storage, catalyst support, and adsorption material.

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