CN112479188A - Silicon-doped graphene aerogel and preparation method and application thereof - Google Patents

Silicon-doped graphene aerogel and preparation method and application thereof Download PDF

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CN112479188A
CN112479188A CN202011325444.4A CN202011325444A CN112479188A CN 112479188 A CN112479188 A CN 112479188A CN 202011325444 A CN202011325444 A CN 202011325444A CN 112479188 A CN112479188 A CN 112479188A
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silicon
graphene aerogel
doped graphene
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graphene
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CN112479188B (en
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姜立运
于琦
蒋剑超
任帅
张永宏
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Shaanxi University of Technology
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    • H—ELECTRICITY
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    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
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    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
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    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
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    • Y02E60/13—Energy storage using capacitors

Abstract

The invention provides a silicon-doped graphene aerogel and a preparation method and application thereof, which are used for preparing the silicon-doped graphene aerogel and researching the electrochemical performance of the silicon-doped graphene aerogel, wherein graphene oxide is used as a carbon source, silicon dioxide is used as a silicon source, and graphene dispersion liquids with different concentrations are prepared; the silicon-doped graphene aerogel with stable and high performance is prepared by a one-step hydrothermal synthesis method. According to the invention, the product obtained through the hydrothermal reaction has a special three-dimensional porous structure, and the interconnected mesopores on the surface of the silicon-doped graphene aerogel inhibit the agglomeration phenomenon of graphene sheets, so that the specific surface area of the macroscopic graphene material is greatly increased. Meanwhile, the three-dimensional porous structure with distinct layers can improve the ion transmission efficiency, so that the electrochemical performance of the silicon-doped graphene aerogel as a supercapacitor electrode is improved.

Description

Silicon-doped graphene aerogel and preparation method and application thereof
[ technical field ] A method for producing a semiconductor device
The invention belongs to the technical field of high-performance super capacitors, and particularly relates to a silicon-doped graphene aerogel and a preparation method and application thereof.
[ background of the invention ]
Graphene is a two-dimensional carbon material (0.334nm) with a single atomic layer thickness, the stable and special crystal structure determines that graphene has excellent thermal conductivity, electrical conductivity, large surface area, good mechanical properties and easily-modified surface chemistry, and compared with the traditional porous carbon material, graphene has high electrical conductivity (10 mm)4～106S/m), large specific surface area (-2675 m)2The graphene aerogel has the characteristics of/g), high Young modulus (-1 TPa), high breaking strength (-130 GPa) and the like, has fewer intrinsic graphene functional groups and poor compatibility with organic solvents, and can generate low on-off ratio and large leakage current when being applied to electronic devices, thereby seriously restricting the functional development of the graphene aerogel.
Aerogel materials generally refer to three-dimensional porous ultra-light solid materials in which nanoparticles are aggregated to form a nanopore structure, and gas-state dispersion media are filled in the nanopores. The carbon aerogel as a novel amorphous nano material has the advantages of large specific surface area, high porosity, stable physical and chemical properties and the like, is particularly suitable for serving as a catalyst and a carrier thereof, and has excellent thermal conductivity and electrical conductivity. Graphene aerogel is a macroscopic three-dimensional porous structure constructed from two-dimensional graphene sheets. The graphene aerogel composite material has the excellent characteristics of graphene and aerogel, and has more excellent electrical conductivity, thermal conductivity and mechanical strength. The main preparation method of the graphene aerogel comprises the following steps: in-situ assembly, templating, chemical cross-linking, and 3D printing techniques. How to promote the electrochemical performance of graphene aerogel, expand the application field of graphene aerogel for the problem that needs to be solved is that this material can obtain abundant application.
[ summary of the invention ]
The invention aims to overcome the defects of the prior art and provides a silicon-doped graphene aerogel and a preparation method and application thereof, so as to solve the technical problems that the electrochemical performance of the graphene aerogel is not improved and the application field of the graphene aerogel is expanded in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
a preparation method of silicon-doped graphene aerogel comprises the following steps:
step 1, mixing natural graphite powder and concentrated sulfuric acid, adding sodium nitrate after stirring to form a mixture A, cooling the mixture A to 0 ℃, adding potassium permanganate, and heating in a water bath to form a slurry B;
step 2, adding deionized water and H into the slurry B2O2After the mixture is changed from brown to light yellow, washing the mixed solution C by dilute hydrochloric acid, centrifuging the washed mixed solution C, and ultrasonically dispersing the centrifuged solution in water to obtain a GO dispersion liquid;
and 3, mixing the GO dispersion liquid with silicon dioxide, carrying out hydrothermal reaction, airing a product, and carrying out vacuum drying to obtain the silicon-doped graphene aerogel.
The invention is further improved in that:
preferably, in the step 1, the mixing ratio of the natural graphite powder to the concentrated sulfuric acid is 1 g: 23mL, 0.5g of sodium nitrate was added.
Preferably, in step 1, 3g of potassium permanganate is correspondingly added to 1g of natural graphene powder.
Preferably, in the step 1, the water bath heating temperature is 35-40 ℃, and the water bath heating time is 30 min.
Preferably, in the step 2, the ultrasonic dispersion time is 3 hours, and the concentration of the GO dispersion liquid is 1-8 mg/mL.
Preferably, in step 3, the mass of silica added is 15% of the mass of the GO dispersion.
Preferably, in step 3, the hydrothermal reaction temperature is 180 ℃ and the hydrothermal reaction time is 12 h.
Preferably, in step 3, the vacuum drying time is 72 h.
The silicon-doped graphene aerogel prepared by the preparation method is formed by winding lamellar graphene sheets, three-dimensional holes are formed among the wound graphene sheets, silicon atoms are doped in the holes, and the size of the holes is 1-100 nm.
An application of the silicon-doped graphene aerogel in the field of capacitors.
Compared with the prior art, the invention has the following beneficial effects:
the invention discloses a preparation method of silicon-doped graphene aerogel, which is simple, adopts a hydrothermal method with a simple synthesis principle and easy control of sample morphology, synthesizes Si-GA with high porosity by taking graphene oxide as a carbon source and silicon dioxide as a silicon source, firstly prepares GO dispersion liquid by an improved Hummers method, increases oxygen-containing functional groups on the GO dispersion liquid after oxidation to make the GO dispersion liquid more active than graphene, and can improve the property of the GO dispersion liquid through various reactions with the oxygen-containing functional groups, and the introduction of the oxygen-containing groups not only enables the graphene oxide to have chemical stability, but also provides surface modification active sites and larger specific surface area for synthesizing graphene base/graphene oxide base materials. And because the basal plane and the edge of the graphene lamellar skeleton are provided with structures with various oxygen-containing functional groups, the conductivity and the band gap of the graphene oxide can be adjusted by regulating the types and the number of the oxygen-containing functional groups, the intrinsic graphene functional groups are fewer and the compatibility with an organic solvent is poor, so that the energy band structure of the graphene can be adjusted by doping non-metal silicon atoms, the performance of the graphene aerogel is further improved, and then the silicon-doped graphene aerogel with high performance is stabilized by utilizing a hydrothermal synthesis method. The synthesis method is simple, expensive experimental equipment is not needed, the cost is greatly reduced, large-area preparation can be carried out, and the hydrothermal method is widely applied due to the simplicity, commercial feasibility and good potential of large-scale production, so that the method has wide application prospect in the aspect of industrial production. The Si-GA with high porosity is synthesized by a one-step hydrothermal method, and the Si-GA shows ultrahigh specific capacitance, good rate performance and long cycle life.
The invention also discloses a silicon-doped graphene aerogel, which is a macroscopic three-dimensional porous structure constructed by two-dimensional graphene sheets. The graphene aerogel composite material has the excellent characteristics of graphene and aerogel, and has more excellent electrical conductivity, thermal conductivity and mechanical strength; the aerogel has a macroscopic three-dimensional porous structure constructed by two-dimensional graphene sheets. The Si-GA is communicated with each other and has a three-dimensional porous structure with clear layers. The Si-GA lamella is completely and effectively stacked to form a boundary with clear layers, the holes of the Si-GA are between several microns and dozens of nanometers, the three-dimensional structure of the interconnected mesopores on the surface of the silicon-doped graphene aerogel prevents the graphene lamella from agglomerating in a large range, and the specific surface area of a macroscopic graphene material is increased, so that the ion transmission efficiency and specific capacitance of the Si-GA are greatly improved, and all the effects are attributed to the restoration of graphene conjugated pi bonds (the aperture ratio can influence the capacitance, and the Si can improve the capacitance performance). Meanwhile, due to the fact that the hydrothermal reaction is carried out, the gauze-shaped graphene is mutually wound due to the chemical crosslinking effect, which is an important reason for forming the three-dimensional porous Si-GA, and the capacitance performance of the graphene aerogel can be improved by the graphene with Si atoms doped in the holes. TGA tests show that a large amount of oxygen-containing functional groups in Si-GA are removed in the hydrothermal reduction process, so that Si-GA has better thermal stability than GO. The prepared Si-GA has high specific capacitance (348.5F/g at 1A/g), excellent rate performance and long cycle life.
The invention also discloses application of the silicon-doped graphene aerogel in the field of capacitors, and the Si-GA obtained through hydrothermal reaction has a three-dimensional porous structure, and shows ultrahigh specific capacitance, good rate performance and long cycle life. The three-dimensional porous structure with distinct layers can improve the ion transmission efficiency, so that the electrochemical performance of the silicon-doped graphene aerogel as a supercapacitor electrode is improved.
[ description of the drawings ]
FIG. 1 is an XRD pattern of the undoped and Si-GA nanoporous structures after 12 hours of hydrothermal growth at 180 ℃.
FIG. 2 is an SEM photograph of Si-GA after hydrothermal growth at 180 ℃ for 12 hours; wherein (a) is 1 μm; (b) the graph is 100 nm.
FIG. 3 is an infrared spectrum of the prepared Si-GA.
FIG. 4 is a thermogravimetric test of Si-GA.
FIG. 5 is an electrochemical test of Si-GA; wherein (a) is a Cyclic Voltammogram (CV) of Si-GA at different scan rates; (b) the figure is a constant current charge-discharge curve (GCD) of Si-GA under different current densities; (c) the graph is a current density-specific capacitance curve of Si-GA; (d) nyquist plot of Si-GA.
FIG. 6 is a test of the cycling stability of Si-GA after 1000 cycles at a current density of 10A/g.
[ detailed description ] embodiments
The invention is described in further detail below with reference to the accompanying drawings:
in the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention; the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; furthermore, unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly and encompass, for example, both fixed and removable connections; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The invention discloses a silicon-doped graphene aerogel and a preparation method and application thereof, and the method comprises the following specific steps:
first step GO preparation: mixing 100-800 mg of natural graphite powder and 20mL of concentrated sulfuric acid, magnetically stirring for 30min, adding 0.5g of sodium nitrate to form a mixture A, wherein the mixture A is a graphite intercalation compound, slowly adding 3g of potassium permanganate after the mixture is cooled to 0 ℃, heating in a water bath to form a mixed slurry B, and heating in the water bath at the temperature of 35-40 ℃ for 30 min. 70mL of deionized water and 10mL of H were added2O2After the mixed solution is changed from brown to light yellow, forming a mixed solution C, washing the formed mixed solution C for tens of times by using dilute hydrochloric acid, wherein the mass concentration of the dilute hydrochloric acid is 5%, adding the mixed solution, centrifuging the mixed solution at a high speed for 30min, removing residual acid, and ultrasonically dispersing the centrifugally washed solution in deionized water for 3h to obtain uniformly dispersed GO dispersion liquids with different concentrations, wherein the concentration of the GO dispersion solution prepared by strongly oxidizing natural crystalline flake graphite by the GO dispersion liquid through an improved Hummers method is 1-8 mg/mL.
The second step GA preparation: uniformly mixing 10ml of GO dispersion (2mg/ml) and silicon dioxide accounting for 15% of the mass of the GO dispersion, transferring the mixture into a stainless steel reaction kettle with a polytetrafluoroethylene lining, sealing the reaction kettle, putting the reaction kettle into an electric heating constant-temperature air blowing drying oven at 180 ℃, reacting for 12 hours, and taking out the reaction kettle after the reaction kettle is cooled to room temperature. And after the surface of the graphene is naturally aired, vacuum drying is carried out for 72 hours at the temperature of 80 ℃, and then the Si-GA is obtained.
An application approach of the Si-GA provided by the invention is as follows: a super capacitor. The specific test process is as follows: a three-electrode system is adopted to test the electrochemical performance of Si-GA as a super capacitor electrode, a cyclic voltammetry curve under different scanning rates, a Si-GA constant current charging and discharging curve under different current densities, a current density-specific capacitance curve and a Nyquist curve.
The Si-GA provided by the invention can be used as a high-performance supercapacitor electrode, the energy band structure of graphene is adjusted through silicon doping, the performance of the graphene aerogel is further improved, and a good theoretical basis is provided for the application of the Si-GA in the field of supercapacitors. The preparation method of Si-GA provided by the invention has the advantages of simple synthesis method, low cost and industrialized production method. The invention will be described in more detail below with reference to the accompanying drawings and preferred embodiments of the invention.
Comparative example 1:
1) 200mg of natural graphite powder and 20mL of concentrated sulfuric acid are mixed, magnetically stirred for 30min, and then 0.5g of sodium nitrate is added. After the mixture is cooled to 0 ℃, 3g of potassium permanganate is slowly added, and the mixture is heated in water bath at 40 ℃ for 30min to form mixed thick slurry. 70mL of deionized water and 10mL of H were then added2O2Washing the formed mixed solution with 1.0mol/L diluted hydrochloric acid, finally centrifuging at high speed, and ultrasonically dispersing the centrifugally washed solution in deionized water for 3 hours to obtain 2mg/ml GO dispersion liquid.
2) Transferring the GO dispersion liquid with the concentration of 2mg/ml to a stainless steel reaction kettle with a polytetrafluoroethylene lining, sealing, putting into an electric heating constant-temperature air blowing drying oven at 180 ℃, reacting for 12 hours, and taking out after the GO dispersion liquid is cooled to the room temperature. And after the surface of the graphene is naturally aired, vacuum drying is carried out for 72 hours, and then the graphene aerogel can be obtained.
The XRD pattern of the reaction product obtained in the comparative example is shown in fig. 1, the ir pattern is shown in fig. 3, and the thermogravimetric test is shown in fig. 4.
Example 1:
1) 100mg of natural graphite powder and 20mL of concentrated sulfuric acid are mixed, magnetically stirred for 30min, and then 0.5g of sodium nitrate is added.
After the mixture was cooled to 0c, 3g of potassium permanganate was slowly added,
2) heating in water bath at 40 deg.C for 30min to obtain mixed thick paste. 70mL of deionized water and 10mL of H were added2O2The resulting mixed solution was washed with dilute hydrochloric acid, centrifuged at high speed, and the centrifuged solution was ultrasonically dispersed in deionized water for 3 hours to obtain a 1mg/mLGO dispersion.
2) Uniformly mixing GO dispersion liquid with the concentration of 1mg/ml and silicon dioxide with the mass of 15% of the GO dispersion liquid, transferring the mixture into a stainless steel reaction kettle with a polytetrafluoroethylene lining, sealing the reaction kettle, putting the reaction kettle into an electric heating constant-temperature air blowing drying oven at 180 ℃, reacting for 12 hours, and taking out the reaction kettle after the reaction kettle is cooled to room temperature. And after the surface of the graphene is naturally aired, vacuum drying is carried out for 72 hours, and then the Si-GA is obtained.
Example 2:
1) 200mg of natural graphite powder and 20ml of concentrated sulfuric acid are mixed, magnetically stirred for 30min and then 0.5g of sodium nitrate is added. After the mixture is cooled to 0 ℃, 3g of potassium permanganate is slowly added, and the mixture is heated in a water bath at 35 ℃ for 30min to form mixed thick slurry. 70ml of deionized water and 15ml of H were added2O2Washing the formed mixed solution with dilute hydrochloric acid, centrifuging at high speed, and ultrasonically dispersing the centrifugally washed solution in deionized water for 3 hours to obtain GO dispersion liquid with the concentration of 2 mg/ml.
2) Uniformly mixing GO dispersion liquid with the concentration of 2mg/ml and 15 wt% of silicon dioxide, transferring the mixture into a stainless steel reaction kettle with a polytetrafluoroethylene lining, sealing the reaction kettle, putting the reaction kettle into an electrothermal constant-temperature air blowing drying oven at 180 ℃, reacting for 12 hours, cooling the reaction kettle to room temperature, and taking the reaction kettle out. And after the surface of the graphene is naturally aired, vacuum drying is carried out for 72 hours, and then the Si-GA is obtained.
The XRD pattern and SEM morphology of the reaction product obtained in example 2 are shown in FIG. 1 and FIG. 2, and Si-GA has a three-dimensional well-defined and interconnected pore structure. The Si-GA lamellar is completely and effectively stacked, holes of the Si-GA with clear boundaries are between several microns and dozens of nanometers, the three-dimensional structure with obvious levels and mutual communication not only prevents the graphene lamellar from agglomerating in a large range, but also increases the specific surface area of the graphene lamellar. As shown in FIG. 3, FT-IR was used to characterize GO and Si-GA at 500-4000cm-1The distribution of the internal functional groups shows that the strength of O-H bonds and alkoxy C-O bonds is greatly weakened, and C ═ O bonds of carboxyl groups and carbonyl groups are completely disappeared, which indicates that a large amount of oxygen-containing functional groups are decomposed in the hydrothermal process. The enhancement of the aromatic C ═ C bond absorption peak illustrates the repair of most graphitic regions of Si — GA.
Referring to fig. 4, which is a thermogravimetric side view, TGA test results of GO and Si-GA at 50-1000 ℃ show that decomposition of some of the remaining oxygen-containing functional groups, scavenging a substantial amount of the oxygen-containing functional groups in Si-GA during hydrothermal reduction, showing that Si-GA possesses better thermal stability than GO, and fig. 4 is a thermogravimetric test plot. FIG. 5 (a) is a graph of Cyclic Voltammograms (CVs) of Si-GA at various scan rates, with the CV curves being rectangular-like in shape at all scan rates and the maximum wrap area of the CV curves at 100mV/s scan rate representing the maximum specific capacitance. FIG. 5 (b) is a graph of Si-GA constant current charge and discharge curves (GCD) at different current densities, all the GCD curves are isosceles triangles, no obvious potential drop is generated, and the specific capacitance of Si-GA as the electrode material of the super capacitor is up to 348.5F/g at a current density of 1A/g. FIG. 5 (c) is a graph showing current density-specific capacitance curves for Si-GA, showing that Si-GA has good rate properties, and these excellent properties are likely due to the large specific surface area and good wettability of Si-GA material to provide channels for electrolyte ion transport. FIG. 5 (d) is a Nyquist plot for Si-GA, showing accurate doping of the Si element, and Si-GA exhibits a lower combined internal resistance, indicating good pure capacitance behavior of Si-GA. Referring to FIG. 6, a cyclic stability test is performed to test the cyclic stability of Si-GA at a high current density of 10A/g after 1000 charge-discharge cycles. The results showed that the capacitance retention of Si-GA was 95.71%, showing good cycle stability.
Example 3:
1) 300mg of natural graphite powder and 20ml of concentrated sulfuric acid are mixed, magnetically stirred for 30min and then 0.5g of sodium nitrate is added. After the mixture is cooled to 0 ℃, 3g of potassium permanganate is slowly added, and the mixture is heated in a water bath at 38 ℃ for 30min to form mixed thick slurry. 70mL of deionized water and 1mLH were added2O2Washing the formed mixed solution with dilute hydrochloric acid, centrifuging at high speed, and ultrasonically dispersing the centrifugally washed solution in deionized water for 3 hours to obtain GO dispersion liquid with the degree of 3 mg/ml.
2) Uniformly mixing GO dispersion liquid with the concentration of 3mg/ml and 15 wt% of silicon dioxide, transferring the mixture into a stainless steel reaction kettle with a polytetrafluoroethylene lining, sealing the reaction kettle, putting the reaction kettle into an electrothermal constant-temperature air blowing drying oven at 180 ℃, reacting for 12 hours, cooling the reaction kettle to room temperature, and taking the reaction kettle out. And after the surface of the graphene is naturally aired, vacuum drying is carried out for 72 hours, and then the Si-GA is obtained.
Example 4:
1) 400mg of natural graphite powder and 20mL of concentrated sulfuric acid are mixed, magnetically stirred for 30min, and then 0.5g of sodium nitrate is added. Etc. ofAfter the mixture is cooled to 0 ℃, 3g of potassium permanganate is slowly added, and the mixture is heated in a water bath at 37 ℃ for 30min to form mixed thick slurry. 70mL of deionized water and 10mLH were added2O2And washing the formed mixed solution by using dilute hydrochloric acid, centrifuging at a high speed, and ultrasonically dispersing the centrifugally washed solution in deionized water for 3 hours to obtain a GO dispersion liquid.
2) Uniformly mixing GO dispersion liquid with the concentration of 4mg/ml and 15 wt% of silicon dioxide, transferring the mixture into a stainless steel reaction kettle with a polytetrafluoroethylene lining, sealing the reaction kettle, putting the reaction kettle into an electrothermal constant-temperature air blowing drying oven with the temperature of 180 ℃, reacting for 12 hours, cooling the reaction kettle to room temperature, and taking the reaction kettle out. And after the surface of the graphene is naturally aired, vacuum drying is carried out for 72 hours, and then the Si-GA is obtained.
Example 5:
1) 500mg of natural graphite powder and 20mL of concentrated sulfuric acid are mixed, magnetically stirred for 30min and then added with sodium nitrate. After the mixture is cooled to 0 ℃, 3g of potassium permanganate is slowly added, and the mixture is heated in water bath at 39 ℃ for 30min to form mixed thick slurry. 70mL of deionized water and 10mLH were added2O2And washing the formed mixed solution by using dilute hydrochloric acid, centrifuging at a high speed, and ultrasonically dispersing the centrifugally washed solution in deionized water for 3 hours to obtain a GO dispersion liquid.
2) Uniformly mixing GO dispersion liquid with the concentration of 5mg/ml and 15 wt% of silicon dioxide, transferring the mixture into a stainless steel reaction kettle with a polytetrafluoroethylene lining, sealing the reaction kettle, putting the reaction kettle into an electrothermal constant-temperature air blowing drying oven at 180 ℃, reacting for 12 hours, cooling the reaction kettle to room temperature, and taking the reaction kettle out. And after the surface of the graphene is naturally aired, vacuum drying is carried out for 72 hours, and then the Si-GA is obtained.
Example 6:
1) 600mg of natural graphite powder and 20mL of concentrated sulfuric acid are mixed, magnetically stirred for 30min, and then 0.5g of sodium nitrate is added. After the mixture is cooled to 0 ℃, 3g of potassium permanganate is slowly added, and the mixture is heated in a water bath at 36 ℃ for 30min to form mixed thick slurry. 70mL of deionized water and 15mLH were added2O2And washing the formed mixed solution by using dilute hydrochloric acid, centrifuging at a high speed, and ultrasonically dispersing the centrifugally washed solution in deionized water for 3 hours to obtain a GO dispersion liquid.
2) Uniformly mixing GO dispersion liquid with the concentration of 6mg/ml and 15 wt% of silicon dioxide, transferring the mixture into a stainless steel reaction kettle with a polytetrafluoroethylene lining, sealing the reaction kettle, putting the reaction kettle into an electrothermal constant-temperature air blowing drying oven with the temperature of 180 ℃, reacting for 12 hours, cooling the reaction kettle to room temperature, and taking the reaction kettle out. And after the surface of the graphene is naturally aired, vacuum drying is carried out for 72 hours, and then the Si-GA is obtained.
Example 7:
1) 700mg of natural graphite powder and 520mL of concentrated sulfuric acid are mixed, and 0.5g of sodium nitrate is added after magnetic stirring for 30 min. After the mixture is cooled to 0 ℃, 3g of potassium permanganate is slowly added, and the mixture is heated in water bath at 37 ℃ for 30min to form mixed thick slurry. 70mL of deionized water and 10mLH were added2O2And washing the formed mixed solution by using dilute hydrochloric acid, centrifuging at a high speed, and ultrasonically dispersing the centrifugally washed solution in deionized water for 3 hours to obtain a GO dispersion liquid.
2) Uniformly mixing 7mg/ml GO dispersion liquid and 15 wt% silicon dioxide, transferring the mixture into a stainless steel reaction kettle with a polytetrafluoroethylene lining, sealing the reaction kettle, putting the reaction kettle into an electrothermal constant-temperature air blowing drying oven at 180 ℃, reacting for 12 hours, cooling the reaction kettle to room temperature, and taking the reaction kettle out. And after the surface of the graphene is naturally aired, vacuum drying is carried out for 72 hours, and then the Si-GA is obtained.
Example 8:
1) 800mg of natural graphite powder and 20mL of concentrated sulfuric acid are mixed, magnetically stirred for 30min, and then 0.5g of sodium nitrate is added. After the mixture is cooled to 0 ℃, 3g of potassium permanganate is slowly added, and the mixture is heated in a water bath at 38 ℃ for 30min to form mixed thick slurry. 70mL of deionized water and 10mLH were added2O2And washing the formed mixed solution by using dilute hydrochloric acid, centrifuging at a high speed, and ultrasonically dispersing the centrifugally washed solution in deionized water for 3 hours to obtain a GO dispersion liquid.
2) Uniformly mixing GO dispersion liquid with the concentration of 8mg/ml and 15 wt% of silicon dioxide, transferring the mixture into a stainless steel reaction kettle with a polytetrafluoroethylene lining, sealing the reaction kettle, putting the reaction kettle into an electrothermal constant-temperature air blowing drying oven at 180 ℃, reacting for 12 hours, cooling the reaction kettle to room temperature, and taking the reaction kettle out. And after the surface of the graphene is naturally aired, vacuum drying is carried out for 72 hours, and then the Si-GA is obtained.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (10)

1. A preparation method of silicon-doped graphene aerogel is characterized by comprising the following steps:
step 1, mixing natural graphite powder and concentrated sulfuric acid, adding sodium nitrate after stirring to form a mixture A, cooling the mixture A to 0 ℃, adding potassium permanganate, and heating in a water bath to form a slurry B;
step 2, adding deionized water and H into the slurry B2O2After the mixture is changed from brown to light yellow, washing the mixed solution C by dilute hydrochloric acid, centrifuging the washed mixed solution C, and ultrasonically dispersing the centrifuged solution in water to obtain a GO dispersion liquid;
and 3, mixing the GO dispersion liquid with silicon dioxide, carrying out hydrothermal reaction, airing a product, and carrying out vacuum drying to obtain the silicon-doped graphene aerogel.
2. The preparation method of the silicon-doped graphene aerogel according to claim 1, wherein in the step 1, the mixing ratio of the natural graphite powder to the concentrated sulfuric acid is 1 g: 23mL, 0.5g of sodium nitrate was added.
3. The preparation method of the silicon-doped graphene aerogel according to claim 1, wherein 3g of potassium permanganate is added to 1g of natural graphene powder in step 1.
4. The preparation method of the silicon-doped graphene aerogel according to claim 1, wherein in the step 1, the water bath heating temperature is 35-40 ℃, and the water bath heating time is 30 min.
5. The preparation method of the silicon-doped graphene aerogel according to claim 1, wherein in the step 2, the ultrasonic dispersion time is 3 hours, and the concentration of the GO dispersion liquid is 1-8 mg/mL.
6. The preparation method of the silicon-doped graphene aerogel according to claim 1, wherein in the step 3, the mass of the added silicon dioxide is 15% of the mass of the GO dispersion liquid.
7. The method for preparing the silicon-doped graphene aerogel according to claim 1, wherein in the step 3, the hydrothermal reaction temperature is 180 ℃ and the hydrothermal reaction time is 12 hours.
8. The preparation method of silicon-doped graphene aerogel according to claim 1, wherein in the step 3, the vacuum drying time is 72 hours.
9. The silicon-doped graphene aerogel prepared by the preparation method of any one of claims 1 to 8, wherein the graphene aerogel is formed by winding lamellar graphene sheets, three-dimensional holes are formed between the wound graphene sheets, silicon atoms are doped in the holes, and the size of the holes is 1 μm to 100 nm.
10. Use of the silicon-doped graphene aerogel according to claim 9 in the field of capacitors.
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