Porous carbon nanomaterial and application thereof in supercapacitor electrode material

Abstract

The invention discloses a porous carbon nanomaterial and application thereof in a supercapacitor electrode material, and belongs to the technical field of nanomaterial preparation and application. According to the invention, hollow mesoporous carbon spheres are prepared by a sacrificial template method, the size and aperture of the hollow mesoporous carbon spheres are regulated and controlled by controlling the addition amount of TPOS and KOH, and doping of N element is realized by a hydrothermal method to prepare the porous carbon nanomaterial. According to the preparation method, glutaraldehyde is introduced in the process of preparing the hollow mesoporous carbon spheres and is subjected to aldolization with fucoidin to construct a three-dimensional cross-linked network, so that disordered aggregation of fucoidin is effectively reduced, the mechanical strength of fucoidin is enhanced, and rapid escape of sulfur and oxygen elements in the carbonization process is reduced; therefore, the problem of insufficient mechanical strength caused by loose molecular chains and poor thermal stability of fucoidin is solved. The porous carbon nanomaterial prepared by the invention has relatively high specific surface area and specific capacitance when being used as a supercapacitor electrode material.

Description

Technical Field

[0001] The invention belongs to the technical field of supercapacitor electrode materials and relates to a porous carbon nanomaterial and an application thereof in supercapacitor electrode materials. Background Art

[0002] Supercapacitors are energy storage devices with high power density, fast charge and discharge rates, long service life, and a wide range of applications. The core of its performance depends on the characteristics of the electrode material, so the development of electrode materials with high conductivity, easy availability of raw materials, low cost, and environmental friendliness has become a current research hotspot. Carbon materials have become the preferred material for supercapacitor electrodes due to their excellent rate performance, high cycle stability, fast electron conduction speed, large specific surface area, adjustable pore structure, and low cost.

[0003] When plant polysaccharides (such as cellulose, starch, fucoidan, etc.) are used as carbon sources, the abundant hydroxyl, carboxyl, amino and other functional groups in their molecular chains can be doped with heteroatoms (O, N, S, etc.) in situ during the carbonization process, significantly improving the surface activity and electronic conductivity of the material. Among them, the sulfate groups (-OSO3 - ) and polyhydroxyl groups can increase the wettability of the material surface and effectively shorten the ion diffusion path. In addition, functional groups containing O or S can provide additional capacity through redox reactions. During the carbonization process, the escape of S or O elements can also promote the formation of mesoporous-microporous composite channels, further improving the ion transfer efficiency. However, the highly polar sulfate groups in fucoidan also make it easy to self-aggregate. At the same time, the high O and S content makes the carbon skeleton of fucoidan easy to collapse during the carbonization process. These characteristics make it difficult for fucoidan to be directly applied to fields that require strict structural stability, such as high-power supercapacitor electrodes, lithium-sulfur battery host materials, fuel cell catalyst supports, etc. Summary of the invention

[0004] In view of the problems and defects in the prior art, the present invention provides a porous carbon nanomaterial and its application in supercapacitor electrode materials. The present invention successfully constructs a three-dimensional cross-linked network structure by introducing glutaraldehyde to react with fucoidan to produce acetal. The formation of this structure effectively inhibits the disordered aggregation of fucoidan and significantly enhances the mechanical strength of fucoidan. At the same time, during the carbonization process, the structure can effectively reduce the rapid escape rate of sulfur and oxygen elements. Through the above technical means, the present invention successfully solves the key problem of insufficient mechanical strength of fucoidan due to loose molecular chains and poor thermal stability, thereby enabling fucoidan to be used as an ideal carbon source for the preparation of high-performance porous carbon materials, and successfully applied to the preparation of supercapacitor electrode materials, providing new ideas and methods for the research and development of high-performance energy storage materials.

[0005] On the one hand, the present invention provides a method for preparing a porous carbon nanomaterial, comprising: cross-linking fucoidan with glutaraldehyde to obtain a precursor solution; mixing tetrapropoxysilane, potassium hydroxide, water and ethanol for reaction, adding the precursor solution, stirring to obtain nanospheres; carbonizing the nanospheres and etching them with sodium hydroxide to obtain hollow mesoporous carbon spheres; and subjecting the hollow mesoporous carbon spheres to a hydrothermal reaction with 1-ethyl-3-methylimidazolium tetrafluoroborate to obtain a porous carbon nanomaterial.

[0006] Furthermore, in the method for preparing the porous carbon nanomaterial provided by the present invention, the mass of the fucoidan is 0.8-1.2 g; The volume of the glutaraldehyde is 3-4 mL; The pH of the precursor solution is prepared to be 5-6.

[0007] Furthermore, in the method for preparing the porous carbon nanomaterial provided by the present invention, the amount of tetrapropoxysilane is 14-28 mmol; The concentration of potassium hydroxide is 1 mol / L, and the volume of potassium hydroxide is 5-25 mL; The volume ratio of water to ethanol is 1~2:1; The temperature of the mixed reaction is 25-35°C, and the time of the mixed reaction is 10-15 minutes; The temperature for preparing the nanospheres is 25-35° C., and the reaction time is 20-26 hours.

[0008] Furthermore, in the method for preparing the porous carbon nanomaterial provided by the present invention, the carbonization temperature of the nanospheres is 500-550° C., and the carbonization time is 4-5 h; The heating rate of the carbonization is 0.5-1°C / min.

[0009] Furthermore, in the method for preparing the porous carbon nanomaterial provided by the present invention, the concentration of the sodium hydroxide is 2 mol / L, and the volume of the sodium hydroxide is 30-35 mL.

[0010] Furthermore, in the method for preparing the porous carbon nanomaterial provided by the present invention, the mass volume ratio of the hollow mesoporous carbon spheres to 1-ethyl-3-methylimidazolium tetrafluoroborate is 1:0.2-0.5.

[0011] Furthermore, in the method for preparing the porous carbon nanomaterial provided by the present invention, the temperature of the hydrothermal reaction is 120-140° C., and the time of the hydrothermal reaction is 3-4 hours.

[0012] In a second aspect, the present invention provides a porous carbon nanomaterial prepared by the above preparation method.

[0013] Furthermore, in the porous carbon nanomaterial provided by the present invention, the specific surface area of ​​the porous carbon nanomaterial is 782~1109m 2 / g, pore size is 3~12nm.

[0014] In a third aspect, the present invention provides the use of porous carbon nanomaterials in preparing supercapacitor electrode materials.

[0015] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages: (1) The present invention uses tetrapropoxysilane (TPOS) as a silicon source to generate a hard template SiO2 and regulate the size of hollow mesoporous carbon spheres (HMCS). Potassium hydroxide not only participates in the hydrolysis reaction of TPOS to generate a SiO2 template, but also acts as an activator to control the pore size and optimize the ion diffusion path. In addition, by controlling the temperature and heating rate of the carbonization process, the stability of the hollow mesoporous carbon sphere structure is maintained, the skeleton collapse caused by rapid pyrolysis is avoided, and the integrity of the material structure is ensured.

[0016] (2) The present invention forms a stable ether bond (COC) through the acetal reaction of glutaraldehyde and fucoidan, effectively inhibiting the disordered aggregation of fucoidan molecular chains and significantly enhancing its mechanical strength. During the carbonization process, the reaction also reduces the rapid escape of sulfur (S) and oxygen (O), maintains the integrity of the carbon skeleton, avoids pore collapse, solves the core problems of fucoidan self-aggregation and poor thermal stability, achieves the coexistence of high porosity and structural stability, and lays the foundation for the preparation of high-performance carbon materials.

[0017] (3) The present invention uses plasma liquid to modify the surface of hollow mesoporous carbon spheres, and significantly enhances the surface wettability and electronic conductivity of the material through nitrogen (N) doping, while promoting the redox reaction. The synergistic effect of high specific surface area and nitrogen doping makes fucoidan an ideal carbon source for the preparation of high-performance porous carbon materials. The present invention has successfully applied it to the preparation of supercapacitor electrode materials, providing new ideas and methods for the research and development of high-performance energy storage materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a scanning electron microscope image of porous carbon nanomaterials. DETAILED DESCRIPTION

[0019] The technical scheme of the present invention is described below in conjunction with the embodiments, but the present invention is not limited to the following embodiments. The experimental methods and detection methods described in each embodiment are conventional methods unless otherwise specified; the reagents and materials described are all commercially available unless otherwise specified.

[0020] The fucoidan (extracted from brown algae) involved in the following examples was purchased from Qingdao Mingyue Hailin Fucoidan Biotechnology Co., Ltd. (Qingdao, Shandong).

[0021] Example 1 1. Preparation of hollow mesoporous carbon spheres Fucoidan (0.8-1.2 g) and GA (glutaraldehyde, 3-4 mL) were added to a phosphoric acid solution (30 mL) at a pH of 5-6 to obtain a precursor solution.

[0022] Under stirring conditions at 30~35℃ water bath, TPOS (tetrapropoxysilane, 7.00mL, 14~28mmol) and KOH (5~25mL, 1mol / L) were added to a round-bottom flask containing a mixed solution of H2O (50~65mL) and EtOH (35~50mL) for 10~15min, and then the precursor solution was added to the round-bottom flask and stirred for 20~26h. After the reaction, the precipitate was separated by centrifugation, washed with deionized water and ethanol three times respectively, and dried at 60℃ overnight. The prepared nanospheres were carbonized under nitrogen at 500~550℃ (0.5~1℃ / min) for 4~5h to obtain carbon-silica composites. Finally, NaOH (30~35mL, 2mol / L) was reacted with the carbon-silica composite for 4h to remove silica and obtain hollow mesoporous carbon spheres, which were recorded as HMCS.

[0023] 2. Preparation method of porous carbon nanomaterials The prepared hollow mesoporous carbon spheres (1 g) were dispersed in a mixed solution of EtOH and H2O (EtOH:H2O=1:1) and ultrasonically dispersed for 15 min. After the ultrasonication, 0.2~0.5 mL [EMIM][BF4] (1-ethyl-3-methylimidazolium tetrafluoroborate) was added and stirred for 2 h. Then it was transferred to a reactor lined with polytetrafluoroethylene and reacted at 120~140 °C for 3~4 h. After the reaction, the precipitate was separated by centrifugation, washed with deionized water and ethanol three times respectively, and dried at 60 °C overnight to obtain a porous carbon nanomaterial, which was recorded as N-HMCS.

[0024] Example 2 This embodiment provides a method for preparing a porous carbon nanomaterial.

[0025] 1. Preparation of hollow mesoporous carbon spheres Fucoidan (0.8 g) and GA (glutaraldehyde, 3 mL) were added to a phosphoric acid solution (30 mL) at pH 5.0 to obtain a precursor solution.

[0026] TPOS (tetrapropoxysilane, 7.00 mL, 14 mmol) and KOH (5 mL, 1 mol / L) were added to a round-bottom flask containing a mixed solution of H2O (50 mL) and EtOH (50 mL) in a 35 °C water bath with stirring. The reaction was continued for 10 min, and the precursor solution was added to the round-bottom flask and stirred for 20 h. After the reaction, the precipitate was separated by centrifugation, washed with deionized water and ethanol three times respectively, and dried at 60 °C overnight. The prepared nanospheres were carbonized under nitrogen at 550 °C (1 °C / min) for 5 h to obtain a carbon-silica composite. Finally, NaOH (30 mL, 2 M) was used to react with the carbon-silica composite for 4 h to remove silica and obtain hollow mesoporous carbon spheres, which were recorded as HMCS-1.

[0027] 2. Preparation method of porous carbon nanomaterials The prepared hollow mesoporous carbon spheres (1 g) were dispersed in a mixed solution of EtOH and H2O (EtOH:H2O=1:1) and ultrasonically dispersed for 15 min. After the ultrasonication, 0.2 mL [EMIM][BF4] (1-ethyl-3-methylimidazolium tetrafluoroborate) was added and stirred for 2 h. Then it was transferred to a reactor lined with polytetrafluoroethylene and reacted at 140 °C for 4 h. After the reaction, the precipitate was separated by centrifugation, washed with deionized water and ethanol three times respectively, and dried at 60 °C overnight to obtain a porous carbon nanomaterial, which was recorded as N-HMCS-1.

[0028] Example 3 This embodiment provides a method for preparing a porous carbon nanomaterial.

[0029] 1. Preparation of hollow mesoporous carbon spheres Fucoidan (1.04 g) and GA (glutaraldehyde, 4 mL) were added to a phosphoric acid solution (30 mL) at pH 5.5 to obtain a precursor solution.

[0030] TPOS (tetrapropoxysilane, 7.00 mL, 17.5 mmol) and KOH (10 mL, 1 mol / L) were added to a round-bottom flask containing a mixed solution of H2O (50 mL) and EtOH (50 mL) under stirring at 30 °C water bath. The reaction was continued for 15 min, and then the precursor solution was added to the round-bottom flask and stirred for 24 h. After the reaction, the precipitate was separated by centrifugation, washed with deionized water and ethanol three times respectively, and dried at 60 °C overnight. The prepared nanospheres were carbonized under nitrogen at 500 °C (1 °C / min) for 5 h to obtain a carbon-silica composite. Finally, NaOH (30 mL, 2 M) was used to react with the carbon-silica composite for 4 h to remove silica and obtain hollow mesoporous carbon spheres, which were recorded as HMCS-2.

[0031] 2. Preparation method of porous carbon nanomaterials The prepared hollow mesoporous carbon spheres (1 g) were dispersed in a mixed solution of EtOH and H2O (EtOH:H2O=1:1) and ultrasonically dispersed for 15 min. After the ultrasonication, 0.4 mL [EMIM][BF4] (1-ethyl-3-methylimidazolium tetrafluoroborate) was added and stirred for 2 h. Then it was transferred to a reactor lined with polytetrafluoroethylene and reacted at 140 ° C for 4 h. After the reaction, the precipitate was separated by centrifugation, washed with deionized water and ethanol three times respectively, and dried at 60 ° C overnight to obtain a porous carbon nanomaterial, which was recorded as N-HMCS-2.

[0032] Example 4 This embodiment provides a method for preparing a porous carbon nanomaterial.

[0033] 1. Preparation of hollow mesoporous carbon spheres Fucoidan (1.00 g) and GA (glutaraldehyde, 4 mL) were added to a phosphoric acid solution (30 mL) at pH 5.5 to obtain a precursor solution.

[0034] TPOS (tetrapropoxysilane, 7.00 mL, 21 mmol) and KOH (15 mL, 1 mol / L) were added to a round-bottom flask containing a mixed solution of H2O (65 mL) and EtOH (35 mL) under stirring at 30 °C water bath. The reaction was continued for 15 min, and the precursor solution was added to the round-bottom flask and stirred for 26 h. After the reaction, the precipitate was separated by centrifugation, washed with deionized water and ethanol three times respectively, and dried at 60 °C overnight. The prepared nanospheres were carbonized under nitrogen at 500 °C (0.5 °C / min) for 4 h to obtain a carbon-silica composite. Finally, NaOH (30 mL, 2 M) was used to react with the carbon-silica composite for 3 h to remove silica and obtain hollow mesoporous carbon spheres, which were recorded as HMCS-3.

[0035] 2. Preparation method of porous carbon nanomaterials The prepared hollow mesoporous carbon spheres (1 g) were dispersed in a mixed solution of EtOH and H2O (EtOH:H2O=1:1) and ultrasonically dispersed for 15 min. After the ultrasonication, 0.6 mL [EMIM][BF4] (1-ethyl-3-methylimidazolium tetrafluoroborate) was added and stirred for 2 h. Then it was transferred to a reactor lined with polytetrafluoroethylene and reacted at 120 °C for 3 h. After the reaction, the precipitate was separated by centrifugation, washed with deionized water and ethanol three times respectively, and dried at 60 °C overnight to obtain a porous carbon nanomaterial, which was recorded as N-HMCS-3. Figure 1 is a SEM image of the porous carbon nanomaterial prepared in this example.

[0036] Example 5 This embodiment provides a method for preparing a porous carbon nanomaterial.

[0037] 1. Preparation of hollow mesoporous carbon spheres Fucoidan (1.20 g) and GA (glutaraldehyde, 4 mL) were added to a phosphoric acid solution (30 mL) at pH 6 to obtain a precursor solution.

[0038] TPOS (tetrapropoxysilane, 7.00 mL, 24.5 mmol) and KOH (20 mL, 1 mol / L) were added to a round-bottom flask containing a mixed solution of H2O (50 mL) and EtOH (50 mL) under stirring at 30 °C water bath. The reaction was continued for 15 min, and then the precursor solution was added to the round-bottom flask and stirred for 24 h. After the reaction, the precipitate was separated by centrifugation, washed with deionized water and ethanol three times respectively, and dried at 60 °C overnight. The prepared nanospheres were carbonized under nitrogen at 500 °C (0.5 °C / min) for 5 h to obtain a carbon-silica composite. Finally, NaOH (30 mL, 2 M) was used to react with the carbon-silica composite for 4 h to remove silica and obtain hollow mesoporous carbon spheres, which were recorded as HMCS-4.

[0039] 2. Preparation method of porous carbon nanomaterials The prepared hollow mesoporous carbon spheres (1 g) were dispersed in a mixed solution of EtOH and H2O (EtOH:H2O=1:1) and ultrasonically dispersed for 15 min. After the ultrasonication, 0.6 mL [EMIM][BF4] (1-ethyl-3-methylimidazolium tetrafluoroborate) was added and stirred for 2 h. Then it was transferred to a reactor lined with polytetrafluoroethylene and reacted at 140 ° C for 4 h. After the reaction, the precipitate was separated by centrifugation, washed with deionized water and ethanol three times respectively, and dried at 60 ° C overnight to obtain a porous carbon nanomaterial, which was recorded as N-HMCS-4.

[0040] Example 6 This embodiment provides a method for preparing a porous carbon nanomaterial.

[0041] 1. Preparation of hollow mesoporous carbon spheres Fucoidan (1.04 g) and GA (glutaraldehyde, 4 mL) were added to a phosphoric acid solution (30 mL) at pH 5.5 to obtain a precursor solution.

[0042] TPOS (tetrapropoxysilane, 7.00 mL, 28 mmol) and KOH (25 mL, 1 mol / L) were added to a round-bottom flask containing a mixed solution of H2O (50 mL) and EtOH (50 mL) under stirring at 30 °C water bath. The reaction was continued for 15 min, and the precursor solution was added to the round-bottom flask and stirred for 24 h. After the reaction, the precipitate was separated by centrifugation, washed with deionized water and ethanol three times respectively, and dried at 60 °C overnight. The prepared nanospheres were carbonized under nitrogen at 500 °C (1 °C / min) for 5 h to obtain a carbon-silica composite. Finally, NaOH (30 mL, 2 M) was used to react with the carbon-silica composite for 4 h to remove silica and obtain hollow mesoporous carbon spheres, which were recorded as HMCS-5.

[0043] 2. Preparation method of porous carbon nanomaterials The prepared hollow mesoporous carbon spheres (1 g) were dispersed in a mixed solution of EtOH and H2O (EtOH:H2O=1:1) and ultrasonically dispersed for 15 min. After the ultrasonication, 1.0 mL [EMIM][BF4] (1-ethyl-3-methylimidazolium tetrafluoroborate) was added and stirred for 2 h. Then it was transferred to a reactor lined with polytetrafluoroethylene and reacted at 140 °C for 4 h. After the reaction, the precipitate was separated by centrifugation, washed with deionized water and ethanol three times respectively, and dried at 60 °C overnight to obtain a porous carbon nanomaterial, which was recorded as N-HMCS-5.

[0044] Comparative Example 1 This comparative example provides a method for preparing a porous carbon nanomaterial.

[0045] 1. Preparation of hollow mesoporous carbon spheres Fucoidan (1.04 g) was added to a phosphoric acid solution (30 mL) at pH 5.5 to obtain a precursor solution.

[0046] TPOS (tetrapropoxysilane, 7.00 mL, 21 mmol) and KOH (15 mL, 1 mol / L) were added to a round-bottom flask containing a mixed solution of H2O (50 mL) and EtOH (50 mL) in a 30 °C water bath with stirring. The reaction was continued for 15 min, and the precursor solution was added to the round-bottom flask and stirred for 24 h. After the reaction, the precipitate was separated by centrifugation, washed with deionized water and ethanol three times respectively, and dried at 60 °C overnight. The prepared nanospheres were carbonized under nitrogen at 500 °C (1 °C / min) for 5 h to obtain a carbon-silica composite. Finally, NaOH (30 mL, 2 M) was used to react with the carbon-silica composite for 4 h to remove silica and obtain hollow mesoporous carbon spheres, which were recorded as HMCS-6.

[0047] 2. Preparation method of porous carbon nanomaterials The prepared hollow mesoporous carbon spheres (1 g) were dispersed in a mixed solution of EtOH and H2O (EtOH:H2O=1:1) and ultrasonically dispersed for 15 min. After the ultrasonication, 0.6 mL [EMIM][BF4] (1-ethyl-3-methylimidazolium tetrafluoroborate) was added and stirred for 2 h. Then it was transferred to a reactor lined with polytetrafluoroethylene and reacted at 140 ° C for 4 h. After the reaction, the precipitate was separated by centrifugation, washed with deionized water and ethanol three times respectively, and dried at 60 ° C overnight to obtain a porous carbon nanomaterial, which was recorded as N-HMCS-6.

[0048] Example 7 This example provides the performance test results of porous carbon nanomaterials.

[0049] 1.BET test results The present invention uses a sacrificial template method to prepare a hollow structure of a porous carbon nanomaterial, wherein TPOS is used as a silicon source of a hard template SiO2, and KOH not only participates in the hydrolysis reaction of TPOS, but also acts as an activator to control the pore size of the hollow mesoporous carbon sphere. Therefore, the present invention regulates the size and pore size of the hollow mesoporous carbon sphere by controlling the addition amount of TPOS and KOH.

[0050] From the data in Table 1, it can be seen that as the amount of TPOS added increases from 14mmol to 24.5mmol, and the volume of KOH increases from 5mL to 20mL, the specific surface area and pore size of the synthesized porous carbon nanomaterial N-HMCS both increase. However, when the amount of TPOS added is further increased to 28mmol and the volume of KOH reaches 25mL, the specific surface area drops significantly to 369m² / g. This indicates that the shell of the synthesized porous carbon nanomaterial is too thin and the pore size is too large, resulting in the collapse of the material structure.

[0051] In addition, the specific surface area of ​​comparative example 1 (N-HMCS-6) is only 578 m 2 / g, and the pore size is also significantly reduced. In contrast, the present invention introduces glutaraldehyde to react with fucoidan to form a stable ether bond (COC), construct a three-dimensional cross-linked network, and effectively reduce the disordered aggregation of fucoidan. At the same time, glutaraldehyde enhances the mechanical strength of fucoidan and reduces the rapid escape of sulfur and oxygen elements during carbonization, thereby solving the problem of insufficient mechanical strength of fucoidan due to loose molecular chains and poor thermal stability. ‌

[0052] Table 1 BET test results of porous carbon nanomaterials

[0053] 2. Electrochemical performance test results (1) Electrochemical performance testing method Electrochemical measurements were performed on a CHI 760 electrochemical workstation (Shanghai Chenhua Instrument Co., Ltd., China). A three-electrode system was tested: Ag / AgCl electrode and Pt sheet were used as reference electrode and counter electrode, respectively, and the electrolyte was 0.5M Na2SO4 aqueous solution. The working electrode was prepared by coating a slurry of porous carbon nanomaterial N-HMCS, acetylene black and polyvinylidene fluoride (PVDF / NMP, 50 mg / mL) in a mass ratio of 7:2:1 on nickel foam (1×1 cm). The working electrode was then dried at 60°C in a vacuum oven for 12 h. The mass loading of porous carbon nanomaterial N-HMCS was 2 mg.

[0054] The specific capacitance of the porous carbon nanomaterial N-HMCS is obtained by the following equation:

[0055] where I (A) and Δt (s) are the applied discharge current and discharge time, respectively. m (g) is the mass of the porous carbon nanomaterial N-HMCS, and ΔV (V) is the discharge voltage range.

[0056] (2) Electrochemical performance test results As shown in Table 2, when the current density is 1A / g and the voltage is -0.9~-0.2V, the mass specific capacitances of N-HMCS-1, N-HMCS-2, N-HMCS-3, N-HMCS-4, N-HMCS-5, N-HMCS-6 and HMCS-3 are 32F / g, 61F / g, 87F / g, 79F / g, 14F / g, 9F / g and 56F / g respectively. Under different preparation conditions, the specific capacitance of porous carbon nanomaterials is significantly different, and the surface modification of hollow mesoporous carbon spheres by plasma liquid and nitrogen doping are used to significantly improve the specific capacitance of porous carbon nanomaterials.

[0057] Table 2 Specific capacitance of porous carbon nanomaterials

[0058] The embodiments described above are part of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. All other embodiments obtained without creative work and related deductions and substitutions made by ordinary technicians in the field under the conditions of the concept of the present invention belong to the scope of protection of the present invention.

Claims

1. A method for preparing a porous carbon nanomaterial, characterized in that: include: The precursor solution was obtained after fucoidan was cross-linked with glutaraldehyde; After tetrapropoxysilane, potassium hydroxide, water and ethanol are mixed and reacted, a precursor solution is added and stirred to obtain nanospheres; the nanospheres are carbonized and etched with sodium hydroxide to obtain hollow mesoporous carbon spheres; the hollow mesoporous carbon spheres and 1-ethyl-3-methylimidazolium tetrafluoroborate are subjected to a hydrothermal reaction to obtain porous carbon nanomaterials.

2. The method for preparing porous carbon nanomaterials according to claim 1, characterized in that: The mass of the fucoidan is 0.8-1.2 g; The volume of the glutaraldehyde is 3-4 mL; The pH of the precursor solution is prepared to be 5-6.

3. The method for preparing porous carbon nanomaterials according to claim 1, characterized in that: The amount of tetrapropoxysilane is 14-28 mmol; The concentration of potassium hydroxide is 1 mol / L, and the volume of potassium hydroxide is 5-25 mL; The volume ratio of water to ethanol is 1~2:1; The temperature of the mixed reaction is 30-35°C, and the time of the mixed reaction is 10-15 minutes; The temperature for preparing the nanospheres is 30-35° C., and the reaction time is 20-26 hours.

4. The method for preparing porous carbon nanomaterials according to claim 1, characterized in that: The carbonization temperature of the nanospheres is 500-550°C, and the carbonization time is 4-5h; The heating rate of the carbonization is 0.5-1°C / min.

5. The method for preparing porous carbon nanomaterials according to claim 1, characterized in that: The concentration of the sodium hydroxide is 2 mol / L, and the volume of the sodium hydroxide is 30-35 mL.

6. The method for preparing porous carbon nanomaterials according to claim 1, characterized in that: The mass volume ratio of the hollow mesoporous carbon spheres to 1-ethyl-3-methylimidazolium tetrafluoroborate is 1:0.2-0.

5.

7. The method for preparing porous carbon nanomaterials according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 120-140° C., and the time of the hydrothermal reaction is 3-4 hours.

8. A porous carbon nanomaterial, characterized in that: Prepared by the method according to any one of claims 1 to 7.

9. The porous carbon nanomaterial according to claim 8, characterized in that: The specific surface area of ​​the porous carbon nanomaterial is 782-1109 m 2 / g, pore size is 3~12nm.

10. Use of the porous carbon nanomaterial according to any one of claims 8 to 9 in preparing supercapacitor electrode materials.

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