Confined-range horizontally-oriented directionally-frozen graphene aerogel and preparation method thereof

Abstract

The invention discloses a confined horizontal orientation directionally frozen graphene aerogel and a preparation method thereof, and aims to provide the confined horizontal orientation directionally frozen graphene aerogel and the preparation method thereof by utilizing an ice crystal confined growth technology to construct a graphene homogeneous confined space and realize regulation and control of the growth direction of ice crystals. Comprising the following steps: S1, preparing graphene oxide; s2, preparing a graphene oxide film; and S3, preparing the confined horizontal orientation directionally frozen graphene aerogel. The directionally-frozen graphene aerogel prepared by the method solves the problem of single orientation direction of the directionally-frozen graphene aerogel, so that the directionally-frozen graphene aerogel has a horizontally-oriented ordered structure.

Description

Technical Field

[0001] The invention belongs to the field of energy materials and nanotechnology, and particularly relates to a confined horizontally oriented frozen graphene aerogel and a preparation method thereof. Background Art

[0002] Graphene is a single-layer sheet formed by a honeycomb arrangement of carbon atoms, with excellent electrical conductivity, thermal conductivity and mechanical properties. Graphene aerogel is a three-dimensional porous structure material formed by self-assembly of graphene sheets. There are various methods for preparing graphene aerogel, such as directional freezing. Directional freezing technology is a method of rapidly freezing a liquid graphene dispersion into a gel under low temperature conditions. During the freezing process, the graphene nanosheets in the graphene dispersion will gradually crystallize and form a highly ordered structure. Directed frozen graphene aerogel is a graphene material with a highly ordered structure and excellent performance. It has a very high specific surface area and porous structure, and has important application value in energy storage, environmental governance, sensors and other fields.

[0003] The preparation of oriented frozen graphene aerogel is that during the freezing process, the water molecules in the liquid graphene dispersion will gradually condense into ice crystals, forming a layer of hydrogel around the ice crystals. This layer of hydrogel can restrict the movement of graphene nanosheets, thereby promoting their orderly arrangement. The preparation process of oriented frozen aerogel needs to be carried out under low temperature conditions. Liquid nitrogen or a refrigerator is usually used to provide a low temperature environment at the bottom, and the ice crystals grow vertically to the bottom. Therefore, the growth direction of most oriented frozen aerogels is usually perpendicular to the bottom. For some devices that require horizontal orientation for heat and electrical conduction, vertically oriented graphene aerogels will no longer be applicable. Therefore, a single orientation direction is difficult to adapt to the current diversified, miniaturized, integrated, intelligent electronic devices and intelligent systems.

[0004] Based on the above problems, the present invention utilizes the technology of ice crystal confined growth to construct a homogeneous confined space of graphene, thereby realizing the regulation of the growth direction of ice crystals, thereby solving the problem of the single orientation direction of oriented frozen graphene aerogel, and making the oriented frozen graphene aerogel have a horizontally oriented ordered structure, which is conducive to its application in diversified emerging scientific and technological fields. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a confined horizontally oriented frozen graphene aerogel and a preparation method, construct a graphene homogeneous confined space, and use the technology of ice crystal confined growth to achieve the regulation of ice crystal growth direction, so that the directional frozen graphene aerogel has a multi-directional and adjustable ordered structure. The present invention provides the following technical solutions:

[0006] S1. Preparation of graphene oxide: Add 8mL of sulfuric acid to a beaker and heat to 80°C, then quickly add 1.7g of sodium nitrite, 1.7g of phosphorus pentoxide, and 2g of flake graphite in several times, and heat at 80°C for 12h. Add it to 80mL of concentrated sulfuric acid in an ice-water bath, and then add 10g of potassium permanganate in batches. After the addition is completed, react at 35°C for 9h. After the reaction is completed, slowly pour the reaction solution into crushed ice, and when the temperature drops to room temperature, add 5% hydrogen peroxide to the reaction solution until the liquid turns bright yellow. Wash twice with 1mol / L dilute hydrochloric acid, wash once with deionized water, and centrifuge at high speed. Freeze-dry the gel-like graphene oxide to obtain graphene oxide.

[0007] S2. Preparation of graphene oxide film: Graphene is dispersed in water to prepare a graphene oxide dispersion of a certain concentration. The prepared graphene oxide dispersion is poured into a culture dish with a liquid level of about 2 to 3 mm. The culture dish is then placed on a hot plate at 50°C and heated for 6 hours. After the water is completely evaporated, a graphene oxide film is formed at the bottom of the culture dish. After naturally cooling to room temperature, the graphene oxide film is obtained.

[0008] S3. Preparation of confined horizontally oriented directionally frozen graphene aerogel: prepare a certain concentration of graphene oxide dispersion. The prepared graphene oxide dispersion and graphene oxide film are placed in a culture dish in order to form a hierarchical structure of graphene dispersion-graphene film-graphene dispersion, and the height of the graphene dispersion is adjustable. The culture dish is then placed in a directional freezing device (a copper table is built in a Dewar flask, and liquid nitrogen is poured onto the surface of the copper table). After freezing, the graphene gel is freeze-dried to obtain confined horizontally oriented directionally frozen graphene aerogel, and finally the prepared confined horizontally oriented directionally frozen graphene aerogel is calcined at high temperature in a tubular furnace, and taken out after naturally cooling to room temperature.

[0009] Furthermore, the concentration of the graphene oxide dispersion described in step S2 is 1-5 mg / mL.

[0010] Furthermore, the concentration of the graphene oxide dispersion described in step S3 is 5-15 mg / mL.

[0011] Furthermore, the hierarchical structure of graphene dispersion liquid-graphene film-graphene dispersion liquid described in step S3 may be 3-9 layers.

[0012] Furthermore, the height of the graphene dispersion described in step S3 is 0.5-1.5 mm.

[0013] Furthermore, in step S3, the temperature of high-temperature calcination of graphene aerogel is 500-800°C.

[0014] Furthermore, in step S3, the heating rate of the high-temperature calcination of the graphene aerogel is 5-10°C / min.

[0015] The confined horizontally oriented and directionally frozen graphene aerogel prepared by the present invention adopts a confined directional freezing method. The present invention uses a graphene film to form a homogeneous confined space, so that ice crystals grow in the confined space and change their growth direction, thereby solving the problem of a single orientation direction of the directionally frozen graphene aerogel, and making the directionally frozen graphene aerogel have a horizontally oriented ordered structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a scanning electron microscope image of the confined horizontally oriented frozen graphene aerogel obtained by the present invention; DETAILED DESCRIPTION

[0017] Three embodiments of the present invention are given below to further illustrate the present invention, rather than to limit the scope of the present invention, so as to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.

[0018] Example 1

[0019] S1. Preparation of graphene oxide: Add 8mL of sulfuric acid to a beaker and heat to 80°C, then quickly add 1.7g of sodium nitrite, 1.7g of phosphorus pentoxide, and 2g of flake graphite in several times, and heat at 80°C for 12h. Add it to 80mL of concentrated sulfuric acid in an ice-water bath, and then add 10g of potassium permanganate in batches. After the addition is completed, react at 35°C for 9h. After the reaction is completed, slowly pour the reaction solution into crushed ice, and when the temperature drops to room temperature, add 5% hydrogen peroxide to the reaction solution until the liquid turns bright yellow. Wash twice with 1mol / L dilute hydrochloric acid, wash once with deionized water, and centrifuge at high speed. Freeze-dry the gel-like graphene oxide to obtain graphene oxide.

[0020] S2. Preparation of graphene oxide film: Graphene is dispersed in water to prepare a 1 mg / mL graphene oxide dispersion. The prepared graphene oxide dispersion is poured into a culture dish with a liquid level of about 2 to 3 mm. The culture dish is then placed on a hot plate at 50°C and heated for 6 hours. After the water is completely evaporated, a graphene oxide film is formed at the bottom of the culture dish. After naturally cooling to room temperature, the graphene oxide film is obtained.

[0021] S3. Preparation of confined horizontally oriented directional frozen graphene aerogel: Prepare 5 mg / mL of graphene oxide dispersion. The prepared graphene oxide dispersion and graphene film are placed in a culture dish in order to form a hierarchical structure of graphene dispersion-graphene film-graphene dispersion, and the height of the graphene dispersion is 1 mm. The culture dish is then placed in a directional freezing device (a copper table is built in a Dewar flask, and liquid nitrogen is poured onto the surface of the copper table). After freezing, the graphene gel is freeze-dried to obtain confined horizontally oriented directional frozen graphene aerogel, and finally the prepared confined horizontally oriented directional frozen graphene aerogel is calcined at high temperature in a tubular furnace, and taken out after naturally cooling to room temperature.

[0022] Example 2

[0023] S1. Preparation of graphene oxide: Add 8mL of sulfuric acid to a beaker and heat to 80°C, then quickly add 1.7g of sodium nitrite, 1.7g of phosphorus pentoxide, and 2g of flake graphite in several times, and heat at 80°C for 12h. Add it to 80mL of concentrated sulfuric acid in an ice-water bath, and then add 10g of potassium permanganate in batches. After the addition is completed, react at 35°C for 9h. After the reaction is completed, slowly pour the reaction solution into crushed ice, and when the temperature drops to room temperature, add 5% hydrogen peroxide to the reaction solution until the liquid turns bright yellow. Wash twice with 1mol / L dilute hydrochloric acid, wash once with deionized water, and centrifuge at high speed. Freeze-dry the gel-like graphene oxide to obtain graphene oxide.

[0024] S2. Preparation of graphene oxide film: Graphene is dispersed in water to prepare a 1 mg / mL graphene oxide dispersion. The prepared graphene oxide dispersion is poured into a culture dish with a liquid level of about 2 to 3 mm. The culture dish is then placed on a hot plate at 50°C and heated for 6 hours. After the water is completely evaporated, a graphene oxide film is formed at the bottom of the culture dish. After naturally cooling to room temperature, the graphene oxide film is obtained.

[0025] S3. Preparation of confined horizontally oriented directional frozen graphene aerogel: Prepare 15 mg / mL of graphene oxide dispersion. The prepared graphene oxide dispersion and graphene film are placed in a culture dish in order to form a hierarchical structure of graphene dispersion-graphene film-graphene dispersion, and the height of the graphene dispersion is 1 mm. The culture dish is then placed in a directional freezing device (a copper table is built in a Dewar flask, and liquid nitrogen is poured onto the surface of the copper table). After freezing, the graphene gel is freeze-dried to obtain confined horizontally oriented directional frozen graphene aerogel, and finally the prepared confined horizontally oriented directional frozen graphene aerogel is calcined at high temperature in a tubular furnace, and taken out after naturally cooling to room temperature.

[0026] Example 3

[0027] S1. Preparation of graphene oxide: Add 8mL of sulfuric acid to a beaker and heat to 80°C, then quickly add 1.7g of sodium nitrite, 1.7g of phosphorus pentoxide, and 2g of flake graphite in several times, and heat at 80°C for 12h. Add it to 80mL of concentrated sulfuric acid in an ice-water bath, and then add 10g of potassium permanganate in batches. After the addition is completed, react at 35°C for 9h. After the reaction is completed, slowly pour the reaction solution into crushed ice, and when the temperature drops to room temperature, add 5% hydrogen peroxide to the reaction solution until the liquid turns bright yellow. Wash twice with 1mol / L dilute hydrochloric acid, wash once with deionized water, and centrifuge at high speed. Freeze-dry the gel-like graphene oxide to obtain graphene oxide.

[0028] S2. Preparation of graphene oxide film: Graphene is dispersed in water to prepare a 5 mg / mL graphene oxide dispersion. The prepared graphene oxide dispersion is poured into a culture dish with a liquid level of about 2 to 3 mm. The culture dish is then placed on a 50°C hot plate and heated for 6 hours. After the water is completely evaporated, a graphene oxide film is formed at the bottom of the culture dish. After naturally cooling to room temperature, the graphene oxide film is obtained.

[0029] S3. Preparation of confined horizontally oriented directional frozen graphene aerogel: Prepare 15 mg / mL of graphene oxide dispersion. The prepared graphene oxide dispersion and graphene film are placed in a culture dish in order to form a hierarchical structure of graphene dispersion-graphene film-graphene dispersion, and the height of the graphene dispersion is 1 mm. The culture dish is then placed in a directional freezing device (a copper table is built in a Dewar flask, and liquid nitrogen is poured onto the surface of the copper table). After freezing, the graphene gel is freeze-dried to obtain confined horizontally oriented directional frozen graphene aerogel, and finally the prepared confined horizontally oriented directional frozen graphene aerogel is calcined at high temperature in a tubular furnace, and taken out after naturally cooling to room temperature.

Claims

1. A confined horizontally oriented frozen graphene aerogel and a preparation method, characterized in that: S1. Preparation of graphene oxide: Add 8mL of sulfuric acid to a beaker and heat to 80°C, then quickly add 1.7g of sodium nitrite, 1.7g of phosphorus pentoxide, and 2g of flake graphite in several times, and heat at 80°C for 12h. Add it to 80mL of concentrated sulfuric acid in an ice-water bath, and then add 10g of potassium permanganate in batches. After the addition is completed, react at 35°C for 9h. After the reaction is completed, slowly pour the reaction solution into crushed ice, and when the temperature drops to room temperature, add 5% hydrogen peroxide to the reaction solution until the liquid turns bright yellow. Wash twice with 1mol / L dilute hydrochloric acid, wash once with deionized water, and centrifuge at high speed. Freeze-dry the gel-like graphene oxide to obtain graphene oxide. S2. Preparation of graphene film: Graphene is dispersed in water to prepare a graphene oxide dispersion of a certain concentration. The prepared graphene oxide dispersion is poured into a culture dish with a liquid level of about 2 to 3 mm. The culture dish is then placed on a hot plate at 50°C and heated for 6 hours. After the water is completely evaporated, a graphene film is formed at the bottom of the culture dish. After naturally cooling to room temperature, the graphene film is taken out to obtain the graphene film. S3. Preparation of confined horizontally oriented directionally frozen graphene aerogel: prepare a certain concentration of graphene oxide dispersion. The prepared graphene oxide dispersion and graphene film are placed in a culture dish in order to form a hierarchical structure of graphene dispersion-graphene film-graphene dispersion, and the height of the graphene dispersion is adjustable. The culture dish is then placed in a directional freezing device (a copper table is built in a Dewar flask, and liquid nitrogen is poured onto the surface of the copper table). After freezing, the graphene gel is freeze-dried to obtain confined horizontally oriented directionally frozen graphene aerogel, and finally the prepared confined horizontally oriented directionally frozen graphene aerogel is calcined at high temperature in a tubular furnace, and taken out after naturally cooling to room temperature.

2. A confined horizontally oriented frozen graphene aerogel and a preparation method according to claim 1, characterized in that: The concentration of the graphene oxide dispersion described in step S2 is 1-5 mg / mL.

3. According to the confined horizontally oriented frozen graphene aerogel and preparation method described in claim 1, it is characterized in that: The concentration of the graphene oxide dispersion described in step S3 is 5-15 mg / mL.

4. A confined horizontally oriented frozen graphene aerogel and a preparation method according to claim 1, characterized in that: The hierarchical structure of graphene dispersion liquid-graphene film-graphene dispersion liquid described in step S3 may be 3-9 layers.

5. A confined horizontally oriented frozen graphene aerogel and a preparation method according to claim 1, characterized in that: The height of the graphene dispersion described in step S3 is 0.5-1.5 mm.

6. A confined horizontally oriented frozen graphene aerogel and a preparation method according to claim 1, characterized in that: The temperature of high-temperature calcination of graphene aerogel in step S3 is 500-800°C.

7. A confined horizontally oriented frozen graphene aerogel and a preparation method according to claim 1, characterized in that; The heating rate of the high-temperature calcination of the graphene aerogel in step S3 is 5-10°C / min.

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