Preparation method and application of nitrogen-oxygen co-doped hierarchical porous carbon

Abstract

The invention discloses a preparation method and application of nitrogen-oxygen co-doped graded porous carbon, the method takes 2, 3, 5, 6-tetra (amino) p-benzoquinone as a carbon precursor and a nitrogen doping agent and potassium trimesic acid as an activating agent and a confinement template, the method comprises the following steps: firstly, grinding and uniformly mixing the 2, 3, 5, 6-tetra (amino) p-benzoquinone and the potassium trimesic acid, transferring into a magnetic boat, then putting into a tubular furnace, and carrying out heat preservation for 2-4 hours; under the protection of argon, heating is performed to prepare the nitrogen-oxygen co-doped hierarchical porous carbon, and the obtained nitrogen-oxygen co-doped hierarchical porous carbon has proper nitrogen-oxygen content and rich hierarchical pore structures. 2, 3, 5, 6-tetra (amino) p-benzoquinone is taken as a carbon precursor and a nitrogen doping agent, potassium trimesic acid is taken as an activating agent and a confinement template, nitrogen-oxygen co-doped hierarchical porous carbon is directly constructed by adopting a one-step method, the specific surface area is between 1321.76 and 1789.52 m < 2 > / g, and the total pore volume is between 0.85 and 1.25 cm < 3 > / g; when the material is used as the positive electrode material of the zinc ion hybrid capacitor, the specific capacitance is 205.02 mAh / g under the current density of 0.1 A / g, and the energy density is up to 182.45 Wh / kg.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of carbon material preparation, and particularly relates to a preparation method of nitrogen-oxygen co-doped hierarchical porous carbon and application thereof. BACKGROUND

[0002] Zinc ion hybrid capacitors have the advantages of high energy density of zinc ion batteries and high power density and long cycle life of supercapacitors, and the cathode material determines the final performance. Carbon materials are the first choice for zinc ion hybrid capacitor cathode materials due to their high specific surface area, high electrical conductivity and excellent stability. It is known that the regulation methods of carbon materials mainly include two kinds: 1. By optimizing the pore structure parameters of carbon materials, the storage of zinc ions is realized. For example, Liu et al. synthesized a phenolic resin with resorcinol and formaldehyde as raw materials as a carbon precursor, and tetrapropyl orthosilicate as a template to provide pore-forming particles, and then removed the silica to obtain mesoporous carbon spheres (Energy Storage Materials, 2020, 25, 858-865). As a cathode material for zinc ion hybrid capacitors, its energy density can reach 129.3 Wh / kg; 2. Introducing heteroatoms such as B, N, P, S, O, etc. to regulate the electronic and charge distribution on the surface of carbon materials and the wettability of the surface. Wang et al. first mixed resorcinol and formaldehyde in an ethanol aqueous solution, then polymerized under hydrothermal conditions, and then prepared nitrogen-phosphorus co-doped carbon microspheres by centrifugation, mixing with diaminophosphoric acid and pyrolysis (Journal of Alloys and Compounds, 2022, 901, 163588).

[0003] Although the above-mentioned methods have achieved certain results in the regulation of the pore structure and surface properties of carbon materials, they are far from meeting the requirements of industrialization, and the material preparation steps are relatively complex. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a method for directly preparing nitrogen-oxygen co-doped hierarchical porous carbon using 2, 3, 5, 6-tetra (amino) p-benzoquinone as a carbon precursor and a nitrogen-doping agent, and potassium trimesate as an activator and a limited template.

[0005] To solve the above technical problems, the present application provides the following technical solutions: A preparation method of nitrogen-oxygen co-doped hierarchical porous carbon, the specific steps are as follows: S1, pretreatment of the reactants: first, 2, 3, 5, 6-tetra (amino) p-benzoquinone and potassium trimesate are ground and uniformly mixed to obtain a reactant; S2, preparation of nitrogen-oxygen co-doped hierarchical porous carbon: the reactants obtained in S1 are placed in a magnetic boat, and then the magnetic boat is placed in the center of a tube furnace. After the air in the tube furnace is discharged by passing argon, the tube furnace is directly heated to 900 DEG C at a heating rate of 5 DEG C / min under the protection of argon, and then kept at 900 DEG C for 1 h. After natural cooling to room temperature, the obtained product is taken out, ground, washed with distilled water, dried, ground, and sieved to obtain nitrogen-oxygen co-doped hierarchical porous carbon.

[0006] Preferably, the mass of the 2, 3, 5, 6-tetra (amino) p-benzoquinone accounts for 3 / 15~3 / 27 of the total mass of the mixture of 2, 3, 5, 6-tetra (amino) p-benzoquinone and potassium trimesate, and the mass ratio of potassium trimesate to 2, 3, 5, 6-tetra (amino) p-benzoquinone is 4~8.

[0007] Preferably, in S1, the mass of the 2, 3, 5, 6-tetra (amino) p-benzoquinone is 3g, and the mass of the potassium trimesate is 18g.

[0008] An application of the nitrogen-oxygen co-doped hierarchical porous carbon includes a zinc ion hybrid capacitor, and the nitrogen-oxygen co-doped hierarchical porous carbon is applied to the zinc ion hybrid capacitor as a positive electrode material.

[0009] The present application has the following beneficial effects: 1. The 2, 3, 5, 6-tetra (amino) p-benzoquinone is used as a carbon precursor, raw materials are cheap and easy to obtain, and a simple carbonization and activation method is used to directly prepare the nitrogen-oxygen co-doped hierarchical porous carbon for the zinc ion hybrid capacitor, which is green and environmentally friendly, and realizes high value-added utilization of chemical products. 2. The cheap potassium trimesate is used as an activator and a limited template, which avoids corrosion of equipment in the use process of a strong alkali activator, realizes an acid-free process in the post-processing process, reduces the preparation cost, and reduces the pollution to the environment. 3. The prepared nitrogen-oxygen co-doped hierarchical porous carbon material has a high specific surface area of 1789.52 m 2 / g. 4. When the prepared nitrogen-oxygen co-doped hierarchical porous carbon is used as a positive electrode material of a zinc ion hybrid capacitor, in a 1 mol / L Zn(CF3SO3)2 aqueous electrolyte, the capacity is 205.02 mAh / g at a current density of 0.1 A / g, and the energy density is as high as 182.45 Wh / kg; the capacity is 127.29 mAh / g at a current density of 20 A / g, and the energy density is still as high as 71.51 Wh / kg, which shows high specific capacitance and large energy density. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1Nitrogen adsorption-desorption isotherm of nitrogen-oxygen co-doped hierarchical porous carbon prepared for the present application embodiment 1, 2, 3. Figure 2 Field emission scanning electron microscope photo of nitrogen-oxygen co-doped hierarchical porous carbon prepared for the present application embodiment 2. Figure 3 Capacity of zinc ion hybrid capacitor with nitrogen-oxygen co-doped hierarchical porous carbon electrode material prepared for the present application embodiment 1, 2, 3 in 1 mol / L Zn(CF3SO3)2 electrolyte changing with current density. Figure 4 Energy density of zinc ion hybrid capacitor with nitrogen-oxygen co-doped hierarchical porous carbon electrode material prepared for the present application embodiment 1, 2, 3 in 1 mol / L Zn(CF3SO3)2 electrolyte changing with power density. DETAILED DESCRIPTION

[0011] The specific embodiments of the present application are further described in detail by the description of the embodiments, to help the person skilled in the art have a more complete, accurate and in-depth understanding of the inventive concept and technical solutions of the present application. For reference Figures 1-4As shown, the specific preparation process of the nitrogen-oxygen co-doped hierarchical porous carbon NO-HPC4 in Example 1 provided by the present application is as follows: S1, pretreatment of the reactants: 3g of 2, 3, 5, 6-tetra (amino) p-benzoquinone is ground and uniformly mixed with 12g of potassium hydroxybenzoate to obtain the reactants; S2, preparation of the nitrogen-oxygen co-doped hierarchical porous carbon: the reactants obtained in step S1 are placed in a magnetic boat, and then the magnetic boat is placed in the center of a tube furnace. After the air in the tube furnace is discharged by passing argon gas, the tube furnace is heated to 900℃ at a heating rate of 5℃ / min under the protection of argon gas, and then kept at this temperature for 1h. After natural cooling to room temperature, the obtained product is taken out, ground, washed with distilled water, dried, ground, and sieved to obtain the nitrogen-oxygen co-doped hierarchical porous carbon. The obtained nitrogen-oxygen co-doped hierarchical porous carbon is named NO-HPC4. The XPS test results show that the nitrogen and oxygen contents of NO-HPC4 are 4.56% and 15.21%, respectively. When NO-HPC4 is used as the positive electrode material of a zinc ion hybrid capacitor, in a 1mol / L Zn(CF3SO3)2 electrolyte, the capacity of NO-HPC4 is 180.77mAh / g at a current density of 0.1A / g, and the energy density is 158.84Wh / kg; the capacity of NO-HPC4 is 98.82mAh / g at a current density of 20A / g, and the energy density is 61.09Wh / kg.The obtained nitrogen-oxygen co-doped hierarchical porous carbon was named NO-HPC8, with nitrogen and oxygen contents of 2.37% and 19.04%, respectively. When used as the positive electrode material of a zinc-ion hybrid capacitor, NO-HPC8 exhibited a capacity of 140.68 mAh / g and an energy density of 125.34 Wh / kg in a 1 mol / L Zn(CF3SO3)2 electrolyte at a current density of 0.1 A / g; at a current density of 20 A / g, the capacity reached 50.44 mAh / g and the energy density was 30.85 Wh / kg. The nitrogen-oxygen co-doped hierarchical porous carbons prepared in Examples 1-3 were used as test samples, and their pore structure parameters, elemental composition, and content were determined. The pore structure parameters of nitrogen-oxygen co-doped hierarchical porous carbon are shown in the following example samples: Average pore size (nm) Specific surface area (m2 g-1) Total pore volume (cm3 g-1) Micropore volume (cm3 g-1) NO-HPC4 2.71 1472.85 0.99 0.33 NO-HPC6 2.84 1789.52 1.25 0.56 NO-HPC8 3.01 1321.76 0.85 0.29 The nitrogen-oxygen co-doped hierarchical porous carbon prepared in this invention has a specific surface area between 1321.76 and 1789.52 m² / g, and a total pore volume between 0.85 and 1.25 cm³ / g. This is due to the presence of abundant holes for electrolyte ion storage and transport, and a honeycomb structure for electron conduction within the nitrogen-oxygen co-doped hierarchical porous carbon material, resulting in a high specific surface area of ​​1789.52 m² / g. The elemental composition and content of the nitrogen-oxygen co-doped hierarchical porous carbon samples are as follows: C1s (at.%) O1s (at.%) N1s (at.%) NO-HPC4 80.23 15.21 4.56 NO-HPC6 77.56 18.56 3.89 NO-HPC8 78.59 19.04 2.37. This invention uses 2,3,5,6-tetra(amino)-p-benzoquinone as a carbon precursor and potassium pyromelliticate as an activator and confining template to directly prepare nitrogen-oxygen co-doped hierarchical porous carbon for zinc ion mixed capacitors via a one-step carbonization and activation method. The preparation process is green and environmentally friendly, with an oxygen content as high as 19.04%. During the preparation process, potassium pyromelliticate is used as an activator and confining template, which enables in-situ doping of nitrogen and oxygen elements in the carbon matrix within the template confinement space. Under the trimming effect of the activator, a hierarchical porous structure with cavities is obtained in the carbon matrix.Experimental results show that the nitrogen-oxygen co-doped hierarchical porous carbon prepared in this invention, when used as the positive electrode material of a zinc-ion hybrid capacitor, exhibits a specific capacitance of 205.02 mAh / g and an energy density as high as 182.45 Wh / kg in a 1 mol / L Zn(CF3SO3)2 electrolyte at a current density of 0.1 A / g; even at a current density of 20 A / g, the specific capacitance remains at 127.29 mAh / g and the energy density remains as high as 71.51 Wh / kg, demonstrating high specific capacitance and high energy density. This invention uses 2,3,5,6-tetra(amino)-p-benzoquinone as the carbon precursor and potassium pyromelliticate as the activator and confinement template. As the temperature rises, 2,3,5,6-tetra(amino)-p-benzoquinone melts, coats, and carbonizes on the surface of potassium pyromelliticate. At high temperatures, potassium pyromelliticate decomposes and polymerizes with 2,3,5,6-tetra(amino)-p-benzoquinone, forming a spatial network structure. Simultaneously, the gases and potassium salts generated during decomposition activate and shape the carbon matrix, creating a hierarchical porous structure. Furthermore, nitrogen and oxygen elements replace some carbon atoms in the carbon matrix. Finally, after washing, filtration, and drying, nitrogen-oxygen co-doped hierarchical porous carbon is obtained. Specifically, using 2,3,5,6-tetra(amino)-p-benzoquinone as a carbon precursor, the raw materials are inexpensive and readily available. A simple carbonization and activation method is used to directly prepare nitrogen-oxygen co-doped hierarchical porous carbon for zinc-ion mixed capacitors. This process is green and environmentally friendly, achieving high added value utilization of chemical products. Specifically, using inexpensive potassium trimellitate as an activator and confinement template avoids the corrosion of equipment caused by strong alkaline activators, achieving an acid-free process in post-processing, reducing preparation costs and mitigating environmental pollution. Specifically, the prepared nitrogen-oxygen co-doped hierarchical porous carbon material has a high specific surface area, reaching 1789.52 m² / g. Specifically, an application of nitrogen-oxygen co-doped hierarchical porous carbon includes zinc-ion mixed capacitors. The nitrogen-oxygen co-doped hierarchical porous carbon is used as a positive electrode material in zinc-ion mixed capacitors. Based on this, the nitrogen-oxygen co-doped hierarchical porous carbon, when used as a positive electrode material in zinc-ion mixed capacitors, exhibits a high specific surface area of ​​1 mol / L. In an aqueous Zn(CF3SO3)2 electrolyte, at a current density of 0.1 A / g, its capacity reaches 205.02 mAh / g, and its energy density is as high as 182.45 Wh / kg; at a current density of 20 A / g, its capacity reaches 127.29 mAh / g, and its energy density is still as high as 71.51 Wh / kg, demonstrating high specific capacitance and large energy density. The above embodiments are merely illustrative of the technical concept of this invention and should not be construed as limiting the scope of protection of this invention. Any modifications made to the technical solution based on the technical concept proposed in this invention fall within the scope of protection of this invention; technologies not covered in this invention can be implemented using existing technologies.

Claims

1. A method for preparing nitrogen-oxygen co-doped hierarchical porous carbon, characterized in that, The specific steps are as follows: S1. Pretreatment of reactants: 2,3,5,6-tetra(amino)-p-benzoquinone and potassium pyromellitic acid are ground and mixed evenly to obtain the reactants; S2. Preparation of nitrogen-oxygen co-doped hierarchical porous carbon: The reactants obtained in S1 were placed in a magnetic boat, and then the magnetic boat was placed in the center of a tube furnace. After purging the air in the tube furnace with argon gas, the furnace was heated directly to 900°C at a heating rate of 5°C / min using argon gas as a protective gas. The temperature was kept constant for 1 hour. After naturally cooling to room temperature, the product was taken out, ground, washed with distilled water, dried, ground again, and sieved to obtain nitrogen-oxygen co-doped hierarchical porous carbon.

2. The method for preparing nitrogen-oxygen co-doped hierarchical porous carbon according to claim 1, characterized in that: The mass of 2,3,5,6-tetra(amino)-p-benzoquinone accounts for 3 / 15 to 3 / 27 of the total mass of the mixture of 2,3,5,6-tetra(amino)-p-benzoquinone and potassium pyromelliticate, and the mass ratio of potassium pyromelliticate to 2,3,5,6-tetra(amino)-p-benzoquinone is between 4 and 8.

3. The method for preparing nitrogen-oxygen co-doped hierarchical porous carbon according to claim 1 and its application, characterized in that: In S1, the mass of 2,3,5,6-tetra(amino)-p-benzoquinone is 3g, and the mass of potassium pyromellitic acid is 12g.

4. An application of nitrogen-oxygen co-doped hierarchical porous carbon as described in any one of claims 1-3, comprising a zinc ion hybrid capacitor, characterized in that, The nitrogen-oxygen co-doped hierarchical porous carbon is used as a positive electrode material in zinc-ion hybrid capacitors.

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