Method for preparing porous graphene and application thereof

Abstract

The invention discloses a method for preparing porous graphene and application thereof, and belongs to the technical field of novel carbon materials. The method comprises the following steps: 1, preparing a graphite intercalation compound: uniformly mixing perchloric acid and nitric acid, and then uniformly mixing with NG to carry out water bath intercalation reaction; 2, a muffle furnace is heated to 800-1000 DEG C in advance, the obtained graphite intercalation compound is placed in the muffle furnace for a heat treatment reaction, and a graphene aggregate can be obtained after heat treatment; and 3, ultrasonic dispersion treatment: preparing a turbid liquid from the graphene aggregate and absolute ethyl alcohol, performing ultrasonic treatment until the graphene aggregate is completely dispersed, and drying to obtain the porous graphene carbon material rich in pore structures. The method disclosed by the invention is simple in preparation process, and can realize macro preparation of the porous graphene with the pore size of 1-100 nanometers.

Description

Technical Field

[0001] The invention belongs to the technical field of novel carbon materials, and in particular relates to a method for preparing porous graphene and application thereof. Background Art

[0002] Porous graphene is a two-dimensional carbon material with nanoscale pores. It not only retains the excellent properties of graphene, such as high conductivity and high specific surface area, but also brings some unique properties due to the presence of pores, such as open band gap, large actual specific surface area, strong mechanical strength and good mass transfer ability. These characteristics make porous graphene show a wide range of application scenarios in the fields of energy, catalysis, environment, micro-nano analysis and sensing.

[0003] However, the preparation process of commonly used porous graphene preparation methods is relatively complicated or costly. For example, the catalytic etching method requires the removal of carbon atoms with the help of a catalyst at a certain temperature, which is a relatively complicated process and requires precise control of catalytic conditions; while the subsequent development of the chemical vapor deposition method (CVD method) has high costs and low yields, is suitable for laboratory use, and is difficult to promote and apply on a large scale.

[0004] Therefore, researching and developing a new method for preparing porous graphene is a research hotspot in this field. Summary of the invention

[0005] In view of the defects existing in the above-mentioned prior art, in order to solve the problem that the preparation method of porous graphene is complicated and costly, the purpose of the present invention is to design and provide a preparation method of porous graphene. The preparation method of the present invention has a simple preparation process, low cost, high yield, and can realize the preparation of porous graphene with pores of 1 to 100 nanometers.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] In one aspect, the present invention provides a method for preparing porous graphene, comprising the following steps:

[0008] (1) Weighing perchloric acid and fuming nitric acid to obtain a mixed solution, adding natural flake graphite (abbreviated as NG), stirring at room temperature, standing, and performing a water bath intercalation reaction to obtain a graphite intercalation compound;

[0009] (2) preheating the muffle furnace, placing the graphite intercalation compound obtained in the above step (1), performing heat treatment, taking it out, and naturally cooling it to room temperature to obtain graphene aggregates;

[0010] (3) The graphene aggregates obtained in the above step (2) are mixed with anhydrous ethanol to obtain a suspension of graphene aggregates, and ultrasonic dispersion is performed until the graphene aggregates are completely dispersed, and then the ultrasound is stopped and the graphene nanosheets are dried to obtain porous graphene nanosheets.

[0011] The method, in step (1), the volume ratio of perchloric acid to fuming nitric acid is 4:1;

[0012] The mass volume ratio of the natural flake graphite to the mixed solution is 1g:0.5-5mL.

[0013] In the method, the stirring time at room temperature in step (1) is 1 to 5 minutes;

[0014] The standing time is 20 to 24 hours.

[0015] In the method, the conditions of the water bath intercalation reaction in step (1) are: temperature 60-70°C, time 72-168h. Preferably, the water bath is heated at 70°C. The water bath temperature should not be too high, otherwise the perchloric acid and nitric acid will be vaporized prematurely.

[0016] The method, the preheating conditions in step (2) are: heating to 800-1000°C at a heating rate of 15°C / min;

[0017] The heat treatment time is 1 to 5 minutes. A muffle furnace is used for high temperature heat treatment. During the high temperature heat treatment, the closed high temperature environment in the muffle furnace can promote the full reaction of the mixed acid and NG.

[0018] In the method described, the mass volume ratio of the graphene aggregates to anhydrous ethanol in step (3) is 1g:10000-20000mL.

[0019] The method, wherein the power of the ultrasonic dispersion in step (3) is 180 W;

[0020] The drying temperature is 60-80°C.

[0021] In a second aspect, the present invention provides the application of any of the methods described in one of the claims in the large-scale preparation of porous graphene.

[0022] A porous graphene prepared by any of the methods described above.

[0023] The porous graphene is used as energy, environment, micro-nano analysis and sensor material.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention introduces a mixed solution of perchloric acid and nitric acid into the interlamellar of natural flake graphite (NG for short) by chemical intercalation and reacts with the carbon hexagonal ring to form a graphite interlayer compound structure. In the subsequent heat treatment process, the mixed acid solution between the NG lamellae further reacts with the carbon hexagonal ring and is gasified at high temperature to form graphene aggregates. Anhydrous ethanol is used as a solvent and ultrasonic dispersion is carried out in an ultrasonic environment. Finally, the dispersion is transferred to an oven for drying to obtain porous graphene.

[0026] 2. The porous graphene prepared by the present invention contains a large number of pore structures with a pore size distribution of 1 to 100 nanometers. The method of the present invention has the characteristics of simple synthesis process, low cost and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a transmission electron microscope image of the porous graphene obtained in Example 1 of the present invention;

[0028] Figure 2 This is a transmission electron microscope image of the porous graphene obtained in Example 2 of the present invention. DETAILED DESCRIPTION

[0029] The present invention will be further described below by means of drawings and embodiments.

[0030] Embodiment 1:

[0031] (1) Preparation of graphite intercalation compound: Mix analytically pure perchloric acid and fuming nitric acid in a beaker at a volume ratio of 4:1 and stir at room temperature for 1 min to obtain a uniform mixed solution. Subsequently, weigh 1 g of 50-mesh NG and pour it into a 20 mL sample bottle. Then slowly add 2.5 mL of the mixed solution to the sample bottle and stir at room temperature for 1 min to transform the mixture into a uniformly mixed viscous slurry. Let it stand at room temperature for 24 h; seal the sample bottle and place it in a water bath for long-term water bath intercalation. The water bath temperature is 70 ° C and the water bath time is 72 h. After the end, the product in the sample bottle is the graphite intercalation compound.

[0032] (2) Preparation of graphene aggregates: The muffle furnace is heated to 800°C at a heating rate of 15°C / min in advance, the graphite intercalation compound is taken out of the sample bottle and placed in a quartz beaker, which is then placed in the muffle furnace for heat treatment reaction. The heat treatment time is 1 min. The quartz beaker is taken out of the muffle furnace using tongs and placed on an insulating pad. The sample is allowed to cool naturally to room temperature to obtain graphene aggregates.

[0033] (3) Ultrasonic dispersion treatment: Graphene aggregates and anhydrous ethanol are placed in a beaker at a mass volume ratio of 1 g:10000 mL to obtain a suspension of graphene aggregates. The suspension is then transferred to an ultrasonic environment of 180 W for ultrasonic dispersion until the graphene aggregates are completely dispersed in the anhydrous ethanol and the ultrasound is stopped. Finally, the graphene dispersion is transferred to an oven at 60° C. for drying to obtain the porous graphene material of the present invention.

[0034] The obtained porous graphene was observed by transmission electron microscopy. Figure 1 As shown, it can be seen that the prepared porous graphene is rich in pore structure.

[0035] Embodiment 2:

[0036] (1) Preparation of graphite intercalation compound: Mix analytically pure perchloric acid and fuming nitric acid in a volume ratio of 4:1 in a beaker and stir at room temperature for 1 min to obtain a uniform mixed solution. Subsequently, weigh 1 g of 50-mesh NG and pour it into a 20 mL sample bottle. Then slowly add 2.5 mL of the mixed solution to the sample bottle and stir at room temperature for 1 min to transform the mixture into a uniformly mixed viscous slurry. Let it stand at room temperature for 24 h; perform the same water bath intercalation on the sample bottle, the water bath temperature is 70 ° C, and the water bath time is increased to 168 h. After completion, the product in the sample bottle is the graphite intercalation compound.

[0037] (2) Preparation of graphene aggregates: The muffle furnace is heated to 800°C at a heating rate of 15°C / min in advance, the graphite intercalation compound is taken out of the sample bottle and placed in a quartz beaker, which is then placed in the muffle furnace for heat treatment reaction. The heat treatment time is 1 min. The quartz beaker is taken out of the muffle furnace using tongs and placed on an insulating pad. The sample is allowed to cool naturally to room temperature to obtain graphene aggregates.

[0038] (3) Ultrasonic dispersion treatment: Graphene aggregates and anhydrous ethanol are placed in a beaker at a mass volume ratio of 1 g:10000 mL to obtain a suspension of graphene aggregates. The suspension is then transferred to an ultrasonic environment of 180 W for ultrasonic dispersion until the graphene aggregates are completely dispersed in the anhydrous ethanol and the ultrasound is stopped. Finally, the graphene dispersion is transferred to an oven at 60° C. for drying to obtain the porous graphene material of the present invention.

[0039] The obtained porous graphene was observed by transmission electron microscopy. Figure 2 As shown, compared with Example 1, the porous graphene obtained in this example contains more pore structures, which indicates that a longer intercalation time can allow more mixed acid solution to enter the NG interlayer structure, thereby etching more pore structures.

[0040] The embodiments of this specific implementation are all preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made according to the structure, shape, principle, etc. of the present invention should be included in the scope of protection of the present invention. The optional materials of various components are listed in the specification of the present invention, but those skilled in the art should understand that the enumeration of the above-mentioned component materials is not restrictive or exhaustive, and various components can be replaced by other equivalent materials not mentioned in the specification of the present invention, and the purpose of the present invention can still be achieved. The specific embodiments mentioned in the specification are also only for the purpose of explanation, not to limit the scope of the present invention. In addition, the dosage range of each component of the present invention includes any combination of any lower limit and any upper limit mentioned in the specification, and also includes any range formed by the specific content of the component in each specific embodiment as an upper limit or a lower limit combination: all these ranges are included in the scope of the present invention, but only to save space, these combined ranges are not listed one by one in the specification. Each feature of the present invention listed in the specification can be combined with any other feature of the present invention, and this combination is also within the scope of the disclosure of the present invention, but only to save space, these combined ranges are not listed one by one in the specification.

Claims

1. A method for preparing porous graphene, characterized in that: The following steps are involved: (1) Weighing perchloric acid and fuming nitric acid to obtain a mixed solution, adding natural flake graphite, stirring at room temperature, standing, and performing a water bath intercalation reaction to obtain a graphite intercalation compound; (2) preheating the muffle furnace, placing the graphite intercalation compound obtained in the above step (1), performing heat treatment, taking it out, and naturally cooling it to room temperature to obtain graphene aggregates; (3) mixing the graphene aggregates obtained in the above step (2) with anhydrous ethanol to obtain a suspension of graphene aggregates, performing ultrasonic dispersion, and drying to obtain porous graphene nanosheets.

2. The method according to claim 1, characterized in that The volume ratio of perchloric acid to fuming nitric acid in step (1) is 4:1; The mass volume ratio of the natural flake graphite to the mixed solution is 1g:0.5-5mL.

3. The method according to claim 1, characterized in that The stirring time at room temperature in step (1) is 1 to 5 minutes; The standing time is 20 to 24 hours.

4. The method according to claim 1, characterized in that The conditions of the water bath intercalation reaction in step (1) are: temperature 60-70° C., time 72-168 h.

5. The method according to claim 1, characterized in that The preheating conditions in step (2) are: heating to 800-1000° C. at a heating rate of 15° C. / min; The heat treatment time is 1 to 5 minutes.

6. The method according to claim 1, characterized in that The mass volume ratio of the graphene aggregates to anhydrous ethanol in step (3) is 1 g: 10000-20000 mL.

7. The method according to claim 1, characterized in that The power of the ultrasonic dispersion in step (3) is 180 W; The drying temperature is 60-80°C.

8. Use of the method according to any one of claims 1 to 8 in preparing porous graphene.

9. A porous graphene prepared by the method according to any one of claims 1 to 8.

10. Use of the porous graphene as claimed in claim 9 as energy, environment, micro-nano analysis and sensor material.

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