Nitrogen-doped three-dimensional structure porous carbon material, and preparation method and application thereof

Abstract

The application relates to a nitrogen-doped three-dimensional structure porous carbon material and a preparation method and application thereof, relates to the technical field of energy, and comprises the following steps: (1) adding 2,6-pyridine dimethyl formaldehyde and p-phenylenediamine into a reaction solvent, uniformly mixing, and then adding acetic acid to perform reaction to obtain a nitrogen-doped three-dimensional structure porous carbon precursor; (2) carbonizing the nitrogen-doped three-dimensional structure porous carbon precursor under an inert gas atmosphere, with a temperature increasing rate of 3-6 DEG C / min, to 600-800 DEG C, and carbonizing for 1.5-2.5 h to obtain the nitrogen-doped three-dimensional structure porous carbon material. The nitrogen-doped three-dimensional structure porous carbon material is obtained by carbonizing a nitrogen-containing polymer obtained by the reaction of 2,6-pyridine dimethyl formaldehyde and p-phenylenediamine as a carbon precursor, and the porous carbon has a three-dimensional superstructure, specifically a nitrogen-doped flower-shaped structure porous carbon or a nitrogen-doped spherical porous carbon, and can be used as an aqueous supercapacitor electrode material and has excellent electrochemical energy storage performance.

Description

Technical Field

[0001] This invention relates to the field of energy technology, specifically to a nitrogen-doped three-dimensional porous carbon material, its preparation method, and its applications. Background Technology

[0002] Carbon materials are a promising electrochemical energy storage material, possessing excellent conductivity, high specific surface area, good electrochemical stability, and low cost, making them the most widely used electrode material for double-layer supercapacitors. Currently, pure carbon materials store energy based on ion adsorption / desorption at the electrode-electrolyte interface, resulting in relatively low specific capacitance; therefore, their electrochemical energy storage performance needs further improvement. Chemical modification of carbon materials can imbue them with more active sites, thereby achieving higher specific capacitance.

[0003] Currently, chemical modification using heteroatom doping can improve the electrochemical performance and specific capacity of carbon materials. Nitrogen atoms are considered the best doping atom for carbon materials due to their excellent chemical properties. Nitrogen doping methods generally fall into two categories: one involves the carbon precursor itself carrying nitrogen, such as polyaniline, polypyrrole, chitosan, and amino acids, which are then carbonized to obtain nitrogen-doped carbon materials; the other involves introducing nitrogen-containing substances, such as urea, ammonia, and ammonium chloride, during the carbonization process. Among these, using nitrogen-containing carbon precursors is the simplest and most efficient method for nitrogen doping. However, most existing nitrogen-containing carbon precursors suffer from complex preparation processes and limited nanostructure types. It is well known that nanostructures have a significant impact on the electrochemical performance of materials, and constructing nitrogen-doped carbon materials with three-dimensional superstructures can maximize the exposure of active surfaces, thereby greatly improving electrochemical energy storage performance. Therefore, how to achieve simple and rapid preparation of nitrogen-doped carbon materials with three-dimensional superstructures remains a hot research area. In view of this, this invention provides a nitrogen-doped three-dimensional porous carbon material, its preparation method, and its applications. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a nitrogen-doped three-dimensional porous carbon material, its preparation method, and its application. The aim is to provide a nitrogen-doped porous carbon material with flower-like or spherical porous structures for use in the electrodes of supercapacitors.

[0005] This invention addresses the aforementioned technical problems by providing a method for preparing nitrogen-doped three-dimensional porous carbon materials, comprising the following steps:

[0006] (1) Add 2,6-pyridinedicarboxaldehyde and p-phenylenediamine to the reaction solvent, mix them evenly, and then add acetic acid to react to obtain a nitrogen-doped three-dimensional porous carbon precursor.

[0007] (2) The nitrogen-doped three-dimensional porous carbon precursor is heated to 600-800℃ in an inert gas atmosphere at a heating rate of 3-6℃ / min and carbonized for 1.5-2.5h to obtain nitrogen-doped three-dimensional porous carbon material.

[0008] The aforementioned 2,6-pyridinedicarboxaldehyde and p-phenylenediamine undergo a polymerization reaction in the presence of acetic acid as a catalyst to generate a nitrogen-doped three-dimensional porous carbon precursor. This precursor is then carbonized at 600-800℃ for 1.5-2.5 h to obtain the nitrogen-doped three-dimensional porous carbon material. The molecular formula of 2,6-pyridinedicarboxaldehyde is C7H5NO4, and its structural formula is [not specified in the original text]. The CAS number is 499-83-2; the molecular formula of p-phenylenediamine is C6H8N2, and its structural formula is... The CAS number is 106-50-3.

[0009] The beneficial effects of this invention are:

[0010] (1) This invention utilizes a nitrogen-containing polymer obtained by reacting 2,6-pyridinedicarboxaldehyde and p-phenylenediamine as a carbon precursor, and obtains nitrogen-doped three-dimensional porous carbon through one-step carbonization, specifically nitrogen-doped flower-shaped porous carbon or nitrogen-doped spherical porous carbon, which can be used as an electrode material for aqueous supercapacitors and has excellent electrochemical energy storage performance.

[0011] (2) The preparation method of the present invention is simple and efficient. The porous carbon obtained has a three-dimensional superstructure and abundant specific surface area. As an electrode material for aqueous supercapacitors, it has high specific capacitance and excellent cycle stability.

[0012] Based on the above technical solution, the present invention can be further improved as follows.

[0013] Further, after the reaction in step (1) is completed, the mixture is filtered, washed, and dried sequentially to obtain a nitrogen-doped three-dimensional porous carbon precursor. Filtration can be performed using any conventional filtration method. The washing agent is the reaction solvent, which can be any one of methanol, 1,2-dichloroethane, 1,4-dioxane, or acetone. Drying is performed under vacuum at a temperature of 50-70°C.

[0014] Furthermore, the reaction solvent in step (1) includes any one or a combination of at least two of methanol, 1,2-dichloroethane, 1,4-dioxane, and acetone.

[0015] Further, in step (1), the molar ratio of 2,6-pyridinedicarboxaldehyde and p-phenylenediamine is 1:(1-1.2); the molar concentration of 2,6-pyridinedicarboxaldehyde in the reaction solvent is 0.025-0.075 mol / L; and the molar concentration of p-phenylenediamine in the reaction solvent is 0.025-0.09 mol / L.

[0016] Furthermore, the molar ratio of acetic acid to p-phenylenediamine is (0.045-0.60):1.

[0017] Furthermore, the inert gas is He, Ne, Ar, or nitrogen (N2).

[0018] Furthermore, the reaction parameters in step (1) are: at room temperature, the reaction is carried out at an ultrasonic power of 80-120W for 10-30 minutes.

[0019] Further, in step (2), the nitrogen-doped three-dimensional porous carbon precursor is heated to 650-800℃ in an inert gas atmosphere at a heating rate of 5℃ / min and carbonized for 2h to obtain nitrogen-doped three-dimensional porous carbon material; the gas flow rate of the inert gas in step (2) is 30-50mL / min.

[0020] A second aspect of this invention provides a nitrogen-doped three-dimensional porous carbon material, which is prepared by any of the methods described above. Specifically, the nitrogen-doped three-dimensional porous carbon material is nitrogen-doped flower-like porous carbon or nitrogen-doped spherical porous carbon.

[0021] A third aspect of the present invention provides an application of a nitrogen-doped three-dimensional porous carbon material, wherein the nitrogen-doped three-dimensional porous carbon material is used in the electrodes of a supercapacitor. Attached Figure Description

[0022] Figure 1 This is a scanning electron microscope image of nitrogen-doped flower-shaped porous carbon provided in Example 1;

[0023] Figure 2 This is a second scanning electron microscope image of nitrogen-doped flower-shaped porous C2 provided in Example 2;

[0024] Figure 3 This is a scanning electron microscope image 3 of nitrogen-doped spherical porous carbon-3 provided in Example 3;

[0025] Figure 4 This is a scanning electron microscope image of nitrogen-doped spherical porous C4 provided in Example 4;

[0026] Figure 5The images show nitrogen adsorption / desorption isotherms and pore size distribution diagrams for Examples 1-6; the left side shows the nitrogen adsorption / desorption isotherms, and the right side shows the pore size distribution diagram.

[0027] Figure 6 These are the constant current charge-discharge curves of Examples 1-6 at a current density of 1 A / g;

[0028] Figure 7 The graphs show the specific capacitance variations of Examples 1-6 under different current densities.

[0029] Figure 8 This is the cyclic stability diagram for Example 1. Detailed Implementation

[0030] The principles and features of this invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they should be performed according to the techniques or conditions described in the literature in this field, or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0031] Example 1

[0032] This embodiment provides a method for preparing nitrogen-doped flower-like porous carbon materials, including the following steps:

[0033] (1) 32.0 mg (0.2962 mmol) of p-phenylenediamine was dissolved in 5 mL of 1,4-dioxane. Separately, 40.5 mg (0.2997 mmol) of 2,6-pyridinedicarboxaldehyde was dissolved in 5 mL of 1,4-dioxane, and the two solutions were then mixed thoroughly. Acetic acid was added as a catalyst, with an amount of 0.6 mL added. After sonication at room temperature for 10 min, the mixture was filtered and washed with 1,4-dioxane to obtain a brownish-yellow solid. Finally, the solid was dried under vacuum at 60 °C to obtain nitrogen-doped flower-like porous carbon precursor 1.

[0034] (2) The nitrogen-doped flower-shaped porous carbon precursor obtained in step (1) was placed in a nitrogen atmosphere with a flow rate of 20 mL / min and heated to 800℃ for 2 h at a heating rate of 5℃ / min. It was then cooled to room temperature naturally to obtain nitrogen-doped flower-shaped porous carbon.

[0035] Example 2

[0036] This embodiment provides a method for preparing nitrogen-doped flower-like porous carbon materials, including the following steps:

[0037] (1) 36.0 mg (0.3333 mmol) of p-phenylenediamine was dissolved in 5 mL of 1,2-dichloroethane. Separately, 40.5 mg of 2,6-pyridinedicarboxaldehyde was dissolved in 5 mL of 1,2-dichloroethane, and the two solutions were then mixed thoroughly. Acetic acid was added as a catalyst, with an amount of 0.6 mL added. After sonication at room temperature for 10 min, the mixture was filtered and washed with 1,2-dichloroethane to obtain a brownish-yellow solid. Finally, the solid was dried under vacuum at 60 °C to obtain nitrogen-doped flower-like porous carbon precursor II.

[0038] (2) The nitrogen-doped flower-shaped porous carbon precursor II obtained in step (1) was placed in a nitrogen atmosphere with a flow rate of 30 mL / min and heated to 800℃ for 2 h at a heating rate of 5℃ / min. It was then naturally cooled to room temperature to obtain nitrogen-doped flower-shaped porous carbon II.

[0039] Example 3

[0040] This embodiment provides a method for preparing nitrogen-doped spherical porous carbon materials, including the following steps:

[0041] (1) 38.0 mg (0.3519 mmol) of p-phenylenediamine was dissolved in 5 mL of acetone. Separately, 40.5 mg of 2,6-pyridinedicarboxaldehyde was dissolved in 5 mL of acetone, and the two solutions were then mixed thoroughly. Acetic acid was added as a catalyst, with an addition amount of 0.6 mL. After sonication at room temperature for 30 min, the mixture was filtered and washed with acetone to obtain a brownish-yellow solid. Finally, the solid was dried under vacuum at 60 °C to obtain nitrogen-doped spherical porous carbon precursor III.

[0042] (2) The nitrogen-doped spherical porous carbon precursor obtained in step (1) was placed in a nitrogen atmosphere with a flow rate of 50 mL / min and heated to 800 °C for 2 h at a heating rate of 5 °C / min. It was then cooled to room temperature naturally to obtain nitrogen-doped spherical porous carbon.

[0043] Example 4

[0044] This embodiment provides a method for preparing nitrogen-doped spherical porous carbon materials, including the following steps:

[0045] (1) 38.0 mg of p-phenylenediamine was dissolved in 5 mL of methanol. Separately, 40.5 mg of 2,6-pyridinedicarboxaldehyde was dissolved in 5 mL of methanol, and the two solutions were then mixed thoroughly. Acetic acid was added as a catalyst, with an addition amount of 0.6 mL. After sonication at room temperature for 10 min, the mixture was filtered and washed with methanol to obtain a brownish-yellow solid. Finally, nitrogen-doped spherical porous carbon precursor tetragenus was obtained by vacuum drying at 60 °C.

[0046] (2) The nitrogen-doped spherical porous carbon precursor obtained in step (1) was placed in a nitrogen atmosphere with a flow rate of 50 mL / min and heated to 800 °C for 2 h at a heating rate of 5 °C / min. It was then cooled to room temperature naturally to obtain nitrogen-doped spherical porous carbon tetrachloride.

[0047] Example 5

[0048] This embodiment provides a method for preparing nitrogen-doped flower-like porous carbon materials, including the following steps:

[0049] (1) 32.0 mg of p-phenylenediamine was dissolved in 5 mL of 1,4-dioxane. Separately, 40.5 mg of 2,6-pyridinedicarboxaldehyde was dissolved in 5 mL of 1,4-dioxane, and the two solutions were then mixed thoroughly. Acetic acid was added as a catalyst, with an addition amount of 0.6 mL. After sonication at room temperature for 10 min, the mixture was filtered and washed with 1,4-dioxane to obtain a brownish-yellow solid. Finally, the solid was vacuum dried at 60 °C to obtain nitrogen-doped flower-like porous carbon precursor V.

[0050] (2) The nitrogen-doped flower-shaped porous carbon precursor 5 obtained in step (1) was placed in a nitrogen atmosphere with a flow rate of 30 mL / min and heated to 600℃ for 2 h at a heating rate of 5℃ / min. It was then naturally cooled to room temperature to obtain nitrogen-doped flower-shaped porous carbon 5.

[0051] Example 6

[0052] This embodiment provides a method for preparing nitrogen-doped flower-like porous carbon materials, including the following steps:

[0053] (1) 32.0 mg of p-phenylenediamine was dissolved in 5 mL of 1,4-dioxane. Separately, 40.5 mg of 2,6-pyridinedicarboxaldehyde was dissolved in 5 mL of 1,4-dioxane, and the two solutions were then mixed thoroughly. Acetic acid was added as a catalyst, with an addition amount of 0.6 mL. After sonication at room temperature for 10 min, the mixture was filtered and washed with 1,4-dioxane to obtain a brownish-yellow solid. Finally, the solid was vacuum dried at 60 °C to obtain nitrogen-doped flower-like porous carbon precursor IVI.

[0054] (2) The nitrogen-doped flower-shaped porous carbon precursor VI obtained in step (1) was placed in a nitrogen atmosphere with a flow rate of 30 mL / min and heated to 700℃ for 2 h at a heating rate of 5℃ / min. It was then naturally cooled to room temperature to obtain nitrogen-doped flower-shaped porous carbon VI.

[0055] To further illustrate the beneficial effects of the present invention, the nitrogen-doped flower-like porous carbon prepared in Examples 1-4 was characterized by scanning electron microscopy (SEM). The specific steps for characterizing the samples using SEM included: fixing the prepared microporous carbon spheres onto the sample stage with conductive adhesive, drying the sample stage in a vacuum drying oven for 12 hours, sputter-coating with gold, and then observing the structural morphology of the samples at 10 kV using a JSM-6330F cold field emission scanning electron microscope manufactured by Nippon Electron Ltd. The results are as follows: Figure 1-4 As shown; by Figure 1-4 It can be seen that different solvents can produce different microstructures. Flower-like structures are obtained in 1,4-dioxane and 1,2-dichloroethane, while porous spherical structures are obtained in acetone and methanol.

[0056] To further illustrate the beneficial effects of the present invention, nitrogen adsorption / desorption tests were performed on the nitrogen-doped three-dimensional porous carbon prepared in Examples 1-6. The obtained adsorption / desorption isotherms and pore size distribution diagrams are shown below. Figure 5 As shown in Table 1, the specific surface area and pore volume data are as follows.

[0057] The nitrogen adsorption-desorption isotherm of the sample was determined using a 3H-2000PM1 adsorption instrument manufactured by Best Instruments Technology Co., Ltd. The specific steps included: weighing 0.05g of the prepared nitrogen-doped three-dimensional porous carbon sample; degassing the sample under vacuum at 250℃ for 6 hours before testing; and determining the specific surface area S. BET The total pore volume was calculated using the BET method, the total pore volume was calculated using the t-polt method, and the total pore size distribution was calculated using DFT theory.

[0058] Table 1. Specific surface area and pore volume data for Examples 1-6

[0059] Example <![CDATA[Specific surface area (S BET ) / m 2 / g]]> <![CDATA[Pore volume / cm 3 / g]]> 1 482.6 0.37 2 532.8 0.38 3 529.9 0.37 4 513.5 0.53 5 415.89 0.32 6 454.25 0.34

[0060] Depend on Figure 5 It can be seen that the specific surface area of ​​Examples 1-6 ranges from 415.89 to 532.8 m². 2 / g, pore volume between 0.32-0.53cm³ 3 / g. The nitrogen adsorption-desorption isotherms of Examples 1-6 are all Type IV. In the region where the initial relative pressure is 0, the adsorption amount increases sharply, indicating that Examples 1-6 all have abundant microporous structures. The pore size distribution curves show that the pore size of Examples 1-6 is mainly concentrated in the range of 0.3-0.5 nm. Table 1 shows that with increasing carbonization temperature, the specific surface area of ​​nitrogen-doped flower-like porous carbon increases, reaching 522.5 nm at a carbonization temperature of 800℃. 2 / g) and pore volume (0.40cm³) 3The nitrogen-doped porous carbon (NOC) prepared with different solvents also exhibited different pore structures, with the NOC prepared using 1,2-dichloroethane as the solvent showing the highest specific surface area (532.8 m² / g). 2 The nitrogen-doped spherical porous carbon pore volume prepared with methanol as solvent was the highest ( / g), with a pore volume of 0.53 cm³. 3 / g) Maximum.

[0061] Application examples

[0062] To further illustrate the beneficial effects of the present invention, the nitrogen-doped three-dimensional porous carbon prepared in Examples 1-6 was used as the electrode material for a supercapacitor. The electrochemical performance of the samples was measured using a CS2350M electrochemical workstation manufactured by Wuhan Koster Instruments Co., Ltd. The specific steps included: mixing nitrogen-doped three-dimensional porous carbon, binder, and conductive agent in a ratio of 8:1:1, rolling the mixture into thin sheets, cutting the material to a size of 1×1cm, and loading it onto a 1×4cm stainless steel mesh. Before testing, the electrode was thoroughly wetted with electrolyte.

[0063] Figure 6 These are the constant current charge-discharge curves of Examples 1-6 at a current density of 1 A / g. Figure 7 Table 1 shows the specific capacitance changes of Examples 1-6 under different current densities, and Table 2 shows the specific capacitance values ​​of Examples 1-6 under different current densities.

[0064] Table 2. Specific capacitance values ​​of Examples 1-6 under different current densities.

[0065]

[0066] Depend on Figure 6 As shown in Table 2, Example 6 has the largest specific capacitance at a current density of 0.2 A / g, reaching 321.6 F / g.

[0067] Depend on Figure 7 As shown in Table 2, Example 1 exhibits excellent rate performance. The specific capacitance reaches 321.6 F / g at a current density of 0.2 A / g, and when the current density increases to 20 A / g, the specific capacitance remains at 155.0 F / g, demonstrating a capacitance retention rate as high as 54.1%.

[0068] Figure 8 This is the cycling stability diagram for Example 1. Example 1, as an electrode material for a supercapacitor, exhibits excellent cycling stability. At a current density of 10 A / g, the specific capacitance retention remains at 99.7% after 5000 cycles.

[0069] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0070] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for producing a nitrogen-doped three-dimensional structure porous carbon material, characterized by, The method comprises the following steps: (1) adding 2,6-pyridine dicarboxaldehyde and p-phenylenediamine into a reaction solvent, mixing uniformly, and then adding acetic acid to react to obtain a nitrogen-doped three-dimensional structure porous carbon precursor; (2) carbonizing the nitrogen-doped three-dimensional structure porous carbon precursor under an inert gas atmosphere at a temperature rising rate of 3-6 ℃ / min to 700-800 ℃ for 1.5-2.5 h to obtain a nitrogen-doped three-dimensional structure porous carbon material; the reaction solvent in step (1) comprises 1,4-dioxane; the molar ratio of the 2,6-pyridine dicarboxaldehyde to the p-phenylenediamine in step (1) is 1:(1-1.2); the substance concentration of the 2,6-pyridine dicarboxaldehyde in the reaction solvent is 0.025-0.075 mol / L; and the substance concentration of the p-phenylenediamine in the reaction solvent is 0.025-0.09 mol / L; the nitrogen-doped three-dimensional structure porous carbon material is specifically a nitrogen-doped flower-shaped structure porous carbon.

2. The method according to claim 1, wherein the molar ratio of the acetic acid to the p-phenylenediamine is (0.045-0.60):

1.

3. The method according to claim 1, wherein the inert gas is helium, neon, argon or nitrogen.

4. The method according to any one of claims 1 to 3, wherein the reaction parameters in step (1) are as follows: reacting at room temperature under ultrasonic power of 80-120 W for 10-30 min.

5. The method according to any one of claims 1 to 3, wherein the method is characterized by, in step (2), the nitrogen-doped three-dimensional structure porous carbon precursor is carbonized under an inert gas atmosphere at a temperature rising rate of 5 ℃ / min to 700-800 ℃ for 2 h to obtain a nitrogen-doped three-dimensional structure porous carbon material; and the gas flow rate of the inert gas in step (2) is 30-50 mL / min.

6. A nitrogen-doped three-dimensional structured porous carbon material, characterized in that, the nitrogen-doped three-dimensional structure porous carbon material is prepared by the method in any one of claims 1 to 5.

7. The nitrogen-doped three-dimensional structure porous carbon material according to claim 6, wherein the nitrogen-doped three-dimensional structure porous carbon material is a nitrogen-doped flower-shaped structure porous carbon.

8. Use of a nitrogen-doped three-dimensional structured porous carbon material, characterized in that the nitrogen-doped three-dimensional structure porous carbon material in claim 6 or 7 is used as an electrode of a supercapacitor.

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