阅读说明：本技术 担载金属氧化物的石墨烯气凝胶及其制备方法和应用 (Graphene aerogel carrying metal oxide, and preparation method and application thereof ) 是由 陈杰 陈文苗 骆艳华 裴晓东 申保金 王凡 邓翔 朱叶峰 于 2021-08-16 设计创作，主要内容包括：本发明公开了一种担载金属氧化物的石墨烯气凝胶及其制备方法和应用,其中该制备方法包括：电解步骤：将金属M作为电极,与含有石墨烯和金属M离子的电解液构成电化学体系,在交流电场下进行电解,得到混合液,其中,石墨烯采用电化学剥离法制备得到；交联步骤：向混合液中加入交联单体,进行交联反应,得到复合交联体；热处理步骤：将复合交联体冷冻干燥并进行热处理,得到担载金属M的氧化物的石墨烯气凝胶。本发明采用电化学剥离法得到的石墨烯,通过电解步骤使得金属M离子在石墨烯片层中嵌入,最终得到金属氧化物与石墨烯均匀分散的复合材料,将该复合材料作为超级电容器的电极材料表现出优异的容量特性。(The invention discloses a metal oxide supported graphene aerogel and a preparation method and application thereof, wherein the preparation method comprises the following steps: an electrolysis step: forming an electrochemical system by using metal M as an electrode and an electrolyte containing graphene and metal M ions, and electrolyzing in an alternating current electric field to obtain a mixed solution, wherein the graphene is prepared by adopting an electrochemical stripping method; a crosslinking step: adding a crosslinking monomer into the mixed solution, and carrying out crosslinking reaction to obtain a composite crosslinked body; a heat treatment step: and (3) freeze-drying and carrying out heat treatment on the composite cross-linked body to obtain the graphene aerogel carrying the metal M oxide. According to the invention, the graphene obtained by an electrochemical stripping method is adopted, metal M ions are embedded in the graphene sheet layer through an electrolysis step, and finally the composite material with uniformly dispersed metal oxide and graphene is obtained, and the composite material is used as an electrode material of a super capacitor to show excellent capacity characteristics.)

1. A preparation method of graphene aerogel carrying metal oxide is characterized by comprising the following steps:

an electrolysis step: forming an electrochemical system by using metal M as an electrode and an electrolyte containing graphene and metal M ions, and electrolyzing in an alternating current electric field to obtain a mixed solution, wherein the graphene is prepared by adopting an electrochemical stripping method;

a crosslinking step: adding a crosslinking monomer into the mixed solution, and carrying out crosslinking reaction to obtain a composite crosslinked body;

a heat treatment step: and (3) freeze-drying and carrying out heat treatment on the composite cross-linked body to obtain the graphene aerogel carrying the metal M oxide.

2. The method of claim 1, wherein the metal M comprises: at least one of manganese, iron, nickel or zinc; and/or the presence of a gas in the gas,

the graphene has a medium oxygen content of less than 10 at.%.

3. The method of claim 1, wherein the crosslinking monomer comprises: one or more of a polymer monomer, graphene oxide, or a carbon nanotube; preferably, the polymer monomers comprise: at least one of aniline, acrylamide, or acrylonitrile.

4. The method of claim 1, wherein the electrochemical stripping process comprises the steps of:

pre-oxidation step: graphite materials are used as a working electrode and a counter electrode, and form a first electrochemical system with electrolyte A, and pre-oxidation treatment is carried out under a first electric field; preferably, the voltage of the first electric field is between 2.5V and 3.5V;

the reaction steps are as follows: forming a second electrochemical system by the working electrode and the counter electrode which are subjected to the pre-oxidation step and an electrolyte B, and carrying out electrochemical stripping reaction under a second electric field to obtain graphene; preferably, the second electric field is an alternating current with a voltage between 5V and 15V.

5. The method according to claim 1, wherein the electrolyte in the electrolytic solution is a nitrate of the metal M ion; preferably, the mass fraction of the electrolyte is between 5% and 50%.

6. The preparation method according to any one of claims 1 to 5, wherein the mass concentration of graphene in the electrolyte is between 0.1mg/mL and 5 mg/mL; and/or the presence of a gas in the gas,

the electrolyte contains a surfactant and/or a pH value regulator; preferably, the surfactant is isopropanol, and the pH regulator is ammonium nitrate; more preferably, the volume fraction of the isopropanol is between 1% and 5%, and the content of the ammonium nitrate is between 5mg/mL and 15 mg/mL.

7. The production method according to claim 1, wherein the composite crosslinked body is immersed in an ethanol solution before the freeze-drying; preferably, the volume fraction of ethanol is from 10% to 20%; and/or the presence of a gas in the gas,

before the freeze-drying, the composite crosslinking body is soaked in ammonia water for treatment; preferably, the volume percentage of the ammonia water is between 1% and 3%.

8. The method of claim 1, wherein the heat treatment is performed at a heating temperature of 100 ℃ to 300 ℃; preferably, the heating temperature is between 180 ℃ and 220 ℃; and/or the presence of a gas in the gas,

the voltage of the alternating current electric field is between 3V and 15V; and/or the presence of a gas in the gas,

the electrolysis time is between 10min and 500 min.

9. Use of the graphene aerogel obtained by the preparation method according to any one of claims 1 to 8 as an electrode material of a supercapacitor.

10. A supercapacitor, characterized in that the electrode contains the graphene aerogel obtained by the preparation method of any one of claims 1 to 8.

Technical Field

The invention relates to the field of graphene composite materials, in particular to a metal oxide supported graphene aerogel and a preparation method and application thereof.

Background

The super capacitor is a novel energy storage device with the advantages of high power density, high charging and discharging speed, long cycle life, no pollution to the environment and the like. The main component of the super capacitor is an electrode, and the design of the electrode with excellent performance is the key for preparing the super capacitor. Graphene is a two-dimensional carbon material composed of hybridized carbon atoms with SP2, and has a high specific surface area (2630 m)²Perg), good mechanical strength (1060GPa), good heat conductivity (5000W/mK), low resistivity (10)^-6Omega cm), wide electrochemical window, good electrochemical stability, etc. These advantages make it one of the important raw materials for preparing electrode materials of supercapacitors. In practical use, however, graphene layers are easy to stack, so that the performance of the graphene-based supercapacitor is far lower than the theoretical value of the graphene-based supercapacitor. In the aspect of improving the performance of the graphene-based capacitor, the graphene and other substances are subjected to composite modification, so that the method is an important method for improving the performance of the graphene.

In recent years, metal oxides (e.g., manganese dioxide) have attracted much attention for use in supercapacitors because of their high specific capacity, abundant reserves, low cost, and environmental friendliness. Especially, the theoretical specific capacitance of the metal oxide is higher, so that the metal oxide becomes an important raw material for preparing electrode materials. However, metal oxides have the disadvantages of poor conductivity, short cycle life, etc., and therefore, in the process of preparing the supercapacitor, the metal oxides are often required to be modified to obtain better capacity. Theoretically, the graphene is compounded with the metal oxide, so that the metal oxide can be effectively utilized to prevent the stacking of graphene sheets, and the effective dispersion of the graphene is realized; meanwhile, the graphene can promote the electron transmission on the surface of the metal oxide, improve the utilization rate of the metal oxide and exert a synergistic effect. However, the preparation of the graphene/metal oxide composite material at present has several problems:

1) graphene used for preparing the composite material is generally prepared by a chemical method, the graphene oxide is reduced by methods such as hydriodic acid or hydrazine hydrate, and the load of metal oxide is realized by modes such as electrochemical deposition and thermal decomposition. As described in patent CN107658147B, the graphene used is the graphene oxide, the mixed solution of the graphene oxide takes graphite, sodium nitrate, concentrated sulfuric acid and potassium permanganate as raw materials to react, and hydrogen peroxide is added at the later stage of the reaction, and the graphene oxide mixed solution is a bright yellow suspension obtained by adding hydrogen peroxide in the process of preparing graphene oxide by a chemical method, which is complex in process and has certain danger.

2) The metal oxide is physically mixed with graphene, or metal salt is reacted with the graphene through solvent heat, the metal oxide is difficult to uniformly disperse among sheets of the graphene, so that the problem of nonuniform dispersion in a composite material in the metal oxide is caused, and when the metal oxide is used as an electrode material of a supercapacitor, the capacity is difficult to fully exert.

Disclosure of Invention

The invention aims to provide a preparation method for conveniently and efficiently preparing graphene and metal oxide, and solves the technical problem that the metal oxide is difficult to uniformly disperse in a graphene sheet layer.

The invention provides a preparation method of graphene aerogel carrying metal oxide, which comprises the following steps: an electrolysis step: forming an electrochemical system by using metal M as an electrode and an electrolyte containing graphene and metal M ions, and electrolyzing in an alternating current electric field to obtain a mixed solution, wherein the graphene is prepared by adopting an electrochemical stripping method; a crosslinking step: adding a crosslinking monomer into the mixed solution, and carrying out crosslinking reaction to obtain a composite crosslinked body; a heat treatment step: and (3) freeze-drying and carrying out heat treatment on the composite cross-linked body to obtain the graphene aerogel carrying the metal M oxide.

In some embodiments, the metal M includes: at least one of manganese, iron, nickel or zinc; and/or the oxygen content in the graphene is less than 10 at.%.

In some embodiments, the crosslinking monomer comprises: one or more of a polymer monomer, graphene oxide, or a carbon nanotube; preferably, the polymer monomers comprise: at least one of aniline, acrylamide, or acrylonitrile.

In some embodiments, the electrochemical peeling method comprises: pre-oxidation step: graphite materials are used as a working electrode and a counter electrode, and form a first electrochemical system with electrolyte A, and pre-oxidation treatment is carried out under a first electric field; preferably, the voltage of the first electric field is between 2.5V and 3.5V; the reaction steps are as follows: forming a second electrochemical system by the working electrode and the counter electrode which are subjected to the pre-oxidation step and the electrolyte B, and carrying out electrochemical stripping reaction in a second electric field to obtain graphene; preferably the second electric field is an alternating current with a voltage between 5V and 15V.

In some embodiments, the electrolyte in the above electrolyte is a nitrate of metal M ions; preferably, the mass fraction of the electrolyte is between 5% and 50%.

In some embodiments, the mass concentration of graphene in the electrolyte is between 0.1mg/mL and 5 mg/mL; and/or the electrolyte contains a surfactant and/or a pH value regulator; preferably, the surfactant is isopropanol, and the pH regulator is ammonium nitrate; more preferably, the volume fraction of isopropanol is between 1% and 5%, and the content of ammonium nitrate is between 5mg/mL and 15 mg/mL.

In some embodiments, prior to freeze-drying, the composite crosslink is immersed in an ethanol solution; preferably, the volume fraction of ethanol is from 10% to 20%; and/or, before freeze-drying, the composite crosslinking body is soaked in ammonia water for treatment; preferably, the percentage by volume of ammonia is between 1% and 3%.

In some embodiments, the heating temperature of the heat treatment is between 100 ℃ and 300 ℃; preferably, the heating temperature is between 180 ℃ and 220 ℃; and/or the voltage of the alternating current electric field is between 3V and 15V; and/or the electrolysis time is between 10min and 500 min.

The invention also provides application of the graphene aerogel obtained by the preparation method as an electrode material of a supercapacitor.

The invention also provides a supercapacitor, wherein an electrode of the supercapacitor contains the graphene aerogel obtained by the preparation method.

Compared with the prior art, the beneficial technical effects of the invention are as follows:

1) according to the preparation method of the graphene aerogel carrying the metal oxide, the graphene prepared by an electrochemical stripping method is used as a raw material, the graphene has a proper oxidation degree (the oxygen content is less than 10 at.%) and proper defect sites, the proper oxidation degree can ensure good electric conductivity of the graphene, and metal ions are embedded in graphene sheet layers in an electrolysis step, and the proper defect sites can be used for anchoring the metal ions, so that the metal ions are uniformly distributed after being embedded between the graphene sheet layers, and the composite material with the metal oxide and the graphene uniformly dispersed is obtained.

2) In the electrolysis step, the metal M is selected as an electrode to form an electrochemical system with the electrolyte containing graphene and metal M ions, the obtained metal M oxide is generated by depositing and oxidizing the metal M ions in the electrolyte and the metal M ions generated by electrolysis of the metal M electrode on the surface of the graphene, and the metal M electrode is selected to be beneficial to improving the content of manganese dioxide in graphene gel.

3) The preparation method further comprises the step of freeze drying after the composite cross-linked body is formed, so that the graphene aerogel with the three-dimensional porous network structure is obtained, and the graphene aerogel serving as the electrode material of the supercapacitor can provide extra capacity and show excellent capacity performance.

4) Compared with graphene prepared by a chemical method and a physical method, the graphene prepared by the electrochemical stripping method has the advantages of low cost and environmental protection, is suitable for batch production, and has industrial practical value.

Drawings

FIG. 1 is a schematic flow chart of a production process in example 3 of the present invention;

fig. 2 is an SEM image of manganese dioxide supported graphene aerogel prepared in example 3 of the present invention;

fig. 3 is a CV test curve of the manganese dioxide supported graphene aerogel in example 3 of the present invention.

Detailed Description

The technical solution of the present invention will be described below by way of specific examples. It is to be understood that one or more of the steps mentioned in the present invention does not exclude the presence of other methods or steps before or after the combined steps, or that other methods or steps may be inserted between the explicitly mentioned steps. It should also be understood that these examples are intended only to illustrate the invention and are not intended to limit the scope of the invention. Unless otherwise indicated, the numbering of the method steps is only for the purpose of identifying the method steps, and is not intended to limit the arrangement order of each method or the scope of the implementation of the present invention, and changes or modifications of the relative relationship thereof may be regarded as the scope of the implementation of the present invention without substantial technical change.

The raw materials and apparatuses used in the examples are not particularly limited in their sources, and may be purchased from the market or prepared according to a conventional method well known to those skilled in the art.

Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.

Example 1

The embodiment provides a preparation method of a graphene aerogel carrying metal oxide, which comprises the following steps:

an electrolysis step: forming an electrochemical system by using metal M as an electrode and an electrolyte containing graphene and metal M ions, and electrolyzing in an alternating current electric field to obtain a mixed solution, wherein the graphene is prepared by adopting an electrochemical stripping method;

a crosslinking step: adding a crosslinking monomer into the mixed solution, and carrying out crosslinking reaction to obtain a composite crosslinked body;

a heat treatment step: and (3) freeze-drying the composite cross-linked body and carrying out heat treatment in an inert environment to obtain the graphene aerogel carrying the metal M oxide.

In some embodiments, the metal M serving as the electrode is manganese metal, and the electrolyte contains manganese ions, so as to finally obtain the manganese dioxide-supported graphene aerogel.

In some embodiments, the metal M serving as the electrode is metallic iron, and the electrolyte contains iron ions, so that the ferroferric oxide-supported graphene aerogel is finally obtained.

In some embodiments, the metal M serving as the electrode is metallic nickel, and the electrolyte contains nickel ions, so as to finally obtain the graphene aerogel supporting nickel oxide.

In some embodiments, the metal M serving as the electrode is metal zinc, and the electrolyte contains zinc ions, so as to obtain the zinc oxide-loaded graphene aerogel.

The graphene prepared by the electrochemical stripping method is used as a raw material, the graphene is prepared in electrolyte systems of different acidic, alkaline and salt solutions by taking a graphite material to be stripped as an electrode by the electrochemical stripping method, ions or charged molecules are driven by current to migrate into graphite layer intervals and push away graphene layers, the whole process is very rapid and can be completed within a few seconds to tens of seconds, and the graphene has the advantages of low cost and environmental protection. In addition, the graphene prepared by electrochemical stripping has proper oxidation degree (oxygen content is less than 10 at.%) and defect sites, the proper oxidation degree can ensure good electrical conductivity of the graphene, and is beneficial to embedding of metal ions in graphene sheet layers in an electrolysis step, and the proper defect sites can be used for anchoring the metal ions, so that the metal ions are uniformly distributed after being embedded between the graphene sheet layers, and the composite material with uniformly dispersed metal oxide and graphene is obtained. The chemically reduced graphene prepared by the common chemical method has poor overall conductivity and too many defects on the graphene, which is not beneficial to ion embedding and uniform dispersion of metal ions in the electrolytic process, while the graphene obtained by physical method stripping has high conductivity, but few defect sites therein are not beneficial to anchoring of the metal ions on the graphene sheet layer, and in addition, the physical method is difficult to prepare a large amount of graphene, so that the graphene is difficult to apply to batch production.

In some embodiments, in the crosslinking step, the crosslinking agent added is one or more of a polymer monomer, graphene oxide, or a carbon nanotube, preferably the polymer monomer is a monomer of a conductive polymer, including but not limited to: aniline, acrylamide or acrylonitrile.

In some embodiments, an electrochemical stripping process, the steps comprising: pre-oxidation step: graphite materials are used as a working electrode and a counter electrode, and form a first electrochemical system with electrolyte A, and pre-oxidation treatment is carried out under a first electric field; preferably, the voltage of the first electric field is between 2.5V and 3.5V; the reaction steps are as follows: forming a second electrochemical system by the working electrode and the counter electrode which are subjected to the pre-oxidation step and the electrolyte B, and carrying out electrochemical stripping reaction in a second electric field to obtain graphene; preferably the second electric field is an alternating current with a voltage between 5V and 15V. Through the pre-oxidation treatment, ions in the electrolyte can be embedded into the graphene layer, and the graphene layer can be stripped more easily in the electrochemical stripping reaction.

In some embodiments, the electrolyte in the electrolyte is a nitrate of the metal M, since the nitrate is easily removed by thermal decomposition in the subsequent heat treatment step, thereby avoiding the introduction of impurities, and preferably, the mass fraction of the electrolyte is between 5% and 50%.

In some embodiments, the graphene mass concentration in the electrolyte is between 0.1mg/mL and 5 mg/mL.

In some embodiments, the electrolyte contains a surfactant and/or a pH adjuster; preferably, the surfactant is isopropanol, and the pH regulator is ammonium nitrate; more preferably, the volume fraction of isopropanol is between 1% and 5%, and the content of ammonium nitrate is between 5mg/mL and 15 mg/mL.

In some embodiments, further comprising the step of: before freeze drying, soaking the composite cross-linked body in ethanol water solution to improve the dispersibility of the composite cross-linked body carrying the metal oxide in a solvent; preferably, the volume fraction of ethanol is from 10% to 20%; and/or before freeze drying, soaking the composite cross-linked body in ammonia water for treatment so as to improve the strength of the graphene aerogel; preferably, the percentage by volume of ammonia is between 1% and 3%.

In some embodiments, the heating temperature of the heat treatment is between 100 ℃ to 300 ℃; preferably, the heating temperature is between 180 ℃ and 220 ℃, and the metal ions in the composite crosslinking body are further oxidized through heat treatment to obtain the metal oxide-loaded graphene aerogel.

In some embodiments, the voltage of the alternating electric field in the electrolyzing step is between 3V and 15V, and the electrolyzing time is between 10min and 500 min; more preferably, the voltage of the alternating current electric field is between 5V and 10V, and the electrolysis time is between 30min and 100 min.

Example 2

The embodiment provides graphene prepared by an electrochemical stripping method, and the preparation method comprises the following steps:

(1) preparation of reactants: pressing graphite powder into graphite flakes through tabletting equipment, wherein the thickness of the pressed flakes is 3 mm; electrolyte A is 0.5mol/L tetrabutylammonium hydrogen sulfate (TBAHSO)₄) Adding 3mL of 30% ammonia water into the electrolyte A according to a volume ratio of 3%, namely adding 3mL of 30% mass fraction ammonia water into each 100mL of the electrolyte A to obtain the electrolyteDecomposing liquid B;

(2) pre-oxidation step: in the step (1), the graphite flake is taken as an electrode, is placed in an electrolyte A, and is stably kept for 2 hours under the direct current voltage of 3V;

(3) the reaction steps are as follows: and (3) placing the electrode in the electrolyte B, electrifying for 1h under 10V alternating current, obtaining a precipitate at the bottom of the solution C, and washing and centrifugally recycling the obtained precipitate to obtain the graphene. The obtained graphene obtained by XPS elemental analysis test has an oxygen content of about 8%, a size exceeding 3 μm, and a number of layers less than 8.

The graphene prepared by the electrochemical stripping method can also adopt a method disclosed in a patent CN 111470499A in the method for electrochemically preparing the graphene, wherein the oxidation degree of the obtained graphene is less than 10 at.%.

Example 3

The embodiment provides a preparation method of manganese dioxide supported graphene aerogel, and the preparation flow is shown in fig. 1, wherein the graphene prepared in embodiment 2 is used as a raw material, and the preparation method comprises the following steps:

preparing an aqueous solution from electrochemically stripped graphene, wherein the concentration of the aqueous solution is 5mg/mL, adding 3 wt% of anhydrous isopropanol, performing ultrasound for 10 minutes, adding 50mg/mL of a manganese nitrate tetrahydrate aqueous solution according to the proportion of 1:4, performing ultrasound for 60 minutes to form a uniform mixed solution, adding ammonium nitrate according to the mass ratio, taking a metal manganese sheet with the length of 5cm, the width of 1cm and the thickness of 2mm as an electrode, applying alternating current of 10V and 50kHz at two ends, and electrolyzing for 60 minutes to obtain a mixed solution B;

adding 1 wt.% of cross-linking agent aniline into the mixed solution B, placing the mixed solution B in an ultrasonic machine, carrying out ultrasonic treatment for 10 minutes at the power of 60W to obtain dispersion liquid C, and transferring the dispersion liquid C into a reaction kettle to react for 2 hours at the temperature of 200 ℃; after the reaction is finished, taking out the sample after the reaction kettle is cooled to room temperature, and soaking the sample in 3% by volume of ammonia water; soaking the sample in an ethanol solution with the volume fraction of 15% before freeze drying, and freeze drying to prepare the manganese salt-loaded graphene aerogel. And finally, placing the graphene oxide aerogel in a tubular furnace for heat treatment at 350 ℃ for 2 hours to obtain the manganese dioxide-loaded graphene aerogel.

Fig. 2 shows a Scanning Electron Microscope (SEM) of the graphene aerogel supporting manganese dioxide, and it can be seen that the graphene aerogel has a three-dimensional porous network structure. The content of Mn ions in the graphene aerogel carrying manganese salt obtained by the test of the Sammerfei ICP inductively coupled plasma spectrometer is 4.4%. As shown in fig. 3, the CV curve of the manganese dioxide-supported graphene aerogel obtained by CV curve measurement using CHI760E showed a mass specific capacitance of 44.29F/g.

Comparative example 1

Graphene in example 3 is replaced with Graphene Oxide (GO) prepared by a chemical method, and the rest conditions are consistent, so that the obtained graphene aerogel is subjected to CV test, and the mass-to-capacitance ratio of the graphene aerogel is 10.96F/g.

Comparative example 2

Graphene in example 3 is replaced with reduced graphene oxide (rGO), the remaining conditions are the same, and the obtained graphene aerogel is subjected to CV test, and the mass-to-capacitance ratio thereof is 28.73F/g.

It can be seen from comparative examples 1 and 2 that the capacity of the manganese dioxide supported graphene aerogel obtained by using graphene obtained by the electrochemical stripping method as a raw material is obviously higher than that of graphene aerogel obtained by using GO and rGO as raw materials, which is related to that graphene obtained by the electrochemical stripping method has a moderate oxidation degree and defect sites.

Comparative example 3

This comparative example is similar to example 3 except that it does not include an electrolysis step, i.e., it does not include a process of performing electrolysis by applying an alternating current of 10V at 50kHz to both ends of a manganese metal sheet having a length of 5cm, a width of 1cm and a thickness of 2mm as an electrode. The rest conditions are consistent, and the content of Mn ions in the obtained graphene aerogel carrying manganese salt is 2.5 at% by the test of a Sammerfei ICP inductively coupled plasma spectrometer. The CV curve measurement was performed by voltammetry using CHI760E, and the mass specific capacitance was 25.6F/g. Therefore, in the comparative example, the content of manganese ions in the obtained graphene aerogel carrying manganese salt is obviously lower than that of the graphene aerogel subjected to electrolysis treatment. The manganese dioxide-loaded graphene gasManganese dioxide in gel from Mn in electrolyte²⁺Mn produced by electrolysis with a manganese metal electrode²⁺Generated by oxidation after the graphene is precipitated on the surface. The selection of the metal manganese electrode is beneficial to the improvement of the content of manganese dioxide in the graphene gel; in the electrolytic treatment, Mn is induced under the action of alternating current²⁺Embedding in graphene sheets, again beneficial to Mn²⁺And uniformly distributing in the graphene sheet layer to finally obtain the graphene aerogel with uniformly distributed manganese dioxide.

Comparative example 4

This comparative example is similar to example 3, except that the manganese salt-supported graphene composite was prepared by ordinary vacuum drying, and the remaining conditions were the same, and the obtained product was measured by a CV curve method using CHI760E to obtain a graphene aerogel having a mass specific capacitance of 15.7F/g, which is significantly lower than that of example 3, because the three-dimensional network structure generated by crosslinking with evaporation of the solvent during ordinary vacuum drying collapses, is difficult to form into an aerogel, and has a significantly reduced specific surface area.

Example 4

The embodiment provides a preparation method of ferroferric oxide supported graphene aerogel, wherein the graphene prepared in the embodiment 2 is used as a raw material, and the preparation method comprises the following steps:

preparing electrochemical stripping graphene into an aqueous solution with the concentration of 3mg/mL, adding 3 wt.% of anhydrous isopropanol, performing ultrasound for 10 minutes, adding 50mg/mL of ferric nitrate aqueous solution according to the proportion of 1:4, performing ultrasound for 60 minutes to form a uniform mixed solution, adding ammonium nitrate according to the mass ratio, taking a metal iron sheet with the length of 5cm, the width of 1cm and the thickness of 2mm as an electrode, applying alternating current of 5V and 50kHz at two ends, and electrolyzing to obtain a mixed solution B;

adding 1 wt.% of cross-linking agent graphene oxide into the mixed solution B, placing the mixed solution B in an ultrasonic machine, carrying out ultrasonic treatment for 10 minutes at the power of 60W to obtain a dispersion liquid C, and transferring the dispersion liquid C into a reaction kettle to react for 12 hours at the temperature of 200 ℃; after the reaction is finished, taking out the sample after the reaction kettle is cooled to room temperature, and soaking the sample in 1% by volume of ammonia water; soaking the sample in an ethanol solution with the volume fraction of 15% before freeze drying, and freeze drying to prepare the graphene aerogel carrying the iron salt. And finally, placing the graphene aerogel in a tubular furnace for heat treatment at 350 ℃ for 2 hours to obtain the ferroferric oxide supported graphene aerogel.

Example 5

The present embodiment provides a preparation method of a graphene aerogel carrying zinc oxide, which has steps similar to those of embodiment 3, and is characterized in that an aqueous solution of ferric nitrate in an electrolyte is replaced by an aqueous solution of zinc nitrate, a metal zinc sheet is used as an electrode, alternating current of 3V and 50kHz is applied to two ends of the metal zinc sheet, and electrolysis is performed for 500min, so as to finally obtain the graphene aerogel carrying zinc oxide.

Example 6

The present example provides a preparation method of a graphene aerogel supporting nickel oxide, which has the steps similar to those of example 4, except that a manganese nitrate aqueous solution in an electrolyte is replaced by a nickel nitrate aqueous solution, a metal nickel sheet is used as an electrode, an alternating current of 15V and 50kHz is applied to two ends of the metal nickel sheet, and electrolysis is performed for 10min, so as to obtain a graphene aerogel supporting nickel oxide.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.