Method for forming graphene film through horizontally tiling and self-assembling graphene

Abstract

The present invention provides a method for forming a graphene film through horizontally tiling and self-assembling graphene, including: proportionally adding toluene and alcohol into a graphene aqueous solution to be fully and uniformly mixed; then pouring the mixture into a vacuum filtration device, wherein when a solution in a filter flask forms a layered solution system with upper and lower layers, graphene is confined at an interface and tiled horizontally under a shear force at the interface to allow (002) planes of graphene to gradually become parallel to the interface, and graphene to be self-assembled to form the graphene film; and activating the suction filtration device to remove the solution, to obtain a graphene film with the (002) planes parallel to each other at a microscopic level on a filter paper.

Claims

1. A method for forming a graphene film through horizontally tiling and self-assembling graphene, comprising: proportionally adding toluene and alcohol into a graphene aqueous solution to be fully and uniformly mixed; then pouring the mixture into a vacuum filtration device, wherein when a solution in a filter flask forms a layered solution system with upper and lower layers, graphene is confined at an interface and tiled horizontally under a shear force at the interface to allow (002) planes of graphene to gradually become parallel to the interface, and graphene to be self-assembled to form the graphene film; and activating the suction filtration device to remove the solution, to obtain a graphene film with the (002) planes parallel to each other at a microscopic level on a filter paper.

2. The method for forming a graphene film through horizontally tiling and self-assembling graphene according to claim 1, comprising: step 1 of dispersing graphene in water and performing ultrasonic treatment to obtain a graphene suspension; step 2 of proportionally adding toluene, alcohol and water into the graphene suspension, and then mixing thoroughly to obtain a mixture A; step 3 of ultrasonically oscillating the mixture A for a short time to uniformly mix the mixture A, and immediately pouring the mixture A into a vacuum suction filtration device, wherein when the mixture A under observation is layered, and the graphene is transferred to the interface until being totally confined at the interface, the graphene is spontaneously horizontally tiled and drifted freely under an interfacial shear force, and the (002) planes of graphene gradually become parallel to the interface while graphene undergoes highly oriented self-assembling; step 4 of activating the vacuum filtration device to remove the solution after the self-assembling is completed to form a stable and uniform graphene film at the interface, to allow the graphene film at the interface to slowly descend as a whole and to be finally completely attached to a surface of the filter paper; and step 5 of drying the filter paper to obtain the graphene film with (002) planes of graphene parallel to each other at a microscopic level.

3. The method for forming a graphene film through horizontally tiling and self-assembling graphene according to claim 2, wherein in the step 1, a concentration of graphene in the graphene suspension is 0.01-2 mg/mL.

4. The method for forming a graphene film through horizontally tiling and self-assembling graphene according to claim 2, wherein in the mixture A, a volume ratio of water to toluene is greater than or equal to 1:8, and a volume ratio of alcohol to toluene is 1:8-2:1.

5. The method for forming a graphene film through horizontally tiling and self-assembling graphene according to claim 2, wherein in the step 3, the mixture A is treated for 5-30 seconds under an ultrasonic power of 30-60 W.

6. The method for forming a graphene film through horizontally tiling and self-assembling graphene according to claim 2, wherein in the step 3, the mixture A under observation is layered after a waiting time of 0.5-5 min.

7. The method for forming a graphene film through horizontally tiling and self-assembling graphene according to claim 2, wherein in the step 5, the drying is performed at a temperature of 25-80° C. for 2-24 hours.

8. The method for forming a graphene film through horizontally tiling and self-assembling graphene to claim 2, further comprising: repeating the step 2 to the step 4 to control a thickness of the graphene film by controlling layer stacking times.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows a layered state of a mixed solution system after standing by for 2 min in a vacuum filtration device in the present invention;

(2) FIG. 2 is a graphene film with (002) planes parallel to each other at the microscopic level obtained after suction filtration for 5 layers; and

(3) FIG. 3 is a comparison diagram of films obtained by an ordinary suction filtration method (a) and the method (b) of the present invention with the same amount of graphene.

DESCRIPTION OF EMBODIMENTS

(4) In order to enable a person skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention. Apparently, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative labor should fall into the protection scope of the present invention.

(5) In addition, the terms “including” and “having” and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or equipment including a series of steps or units need not to be limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or equipment.

(6) The invention will be described in further detail with reference to the accompanying drawings:

(7) The invention provides a method for forming a graphene film through horizontally tiling and self-assembling graphene, which comprises the following steps:

(8) a) graphene is dispersed in water, and ultrasonic treatment is performed to enable graphene to form a stable suspension in a short time, the concentration of graphene being 0.01-2 mg/ml, preferably 0.5-1 mg/ml;

(9) b) a certain amount of the suspension in step a) is taken out, water, alcohol and toluene are added, and the use amounts of the three liquids are adjusted to achieve a predetermined proper volume ratio among the three liquids to obtain a mixture A, the volume ratio of water to toluene should be greater than or equal to 1:8 without an upper limit, the volume ratio of alcohol to toluene is between 1:8 and 2:1, and the preferred volume ratio of water, alcohol and toluene is 1:1:2;

(10) c) the mixture A was ultrasonically oscillated to be mixed uniformly in a short time, and then poured into a suction filtration device, the ultrasonic power is between 30 W and 60 W, and the time is between 5-30 s;

(11) d) within a few minutes, the mixture A is layered, and graphene is gradually transferred to the interface, and finally all of the graphene is confined at the interface; at the same time, graphene reaching the interface is spontaneously horizontally tiled and drifts freely under the action of interfacial shear force, and the planes (002) gradually become parallel to the interface while the graphene undergoes highly oriented self-assembling; the waiting time is 0.5-5 min, and the preferred waiting time is 1-2 min;

(12) e) after the self-assembling is completed, a stable and uniform graphene film is formed at the interface, which is even and flat when viewed from the side and has a stable structure;

(13) f) the suction filtration device is activated to suction out the solution, the graphene film at the interface slowly descends as a whole and is finally completely attached to the surface of the filter paper; and

(14) g) the filter paper is dried to obtain a graphene film with (002) planes of graphene parallel to each other on the microscopic level; the drying temperature is 25-80° C., and the preferred temperature is 60° C.; the drying time is 2-24 hours, and the preferred time is 12 hours.

Example 1

(15) a) Highly conductive graphene (TNERGO-50, Chengdu organic chemistry co., ltd., Chinese academy of sciences) was dispersed in water and subjected to ultrasonic treatment to form a stable suspension in a short time, and the graphene concentration was 1 mg/mL;

(16) b) 1 mL of the suspension prepared in step a) was taken out, water, alcohol and toluene were added therein, and the use amounts of the three liquids were adjusted to achieve a predetermined proper volume ratio of 1:1:2 to obtain a mixture A;

(17) c) the mixture A was ultrasonically oscillated to be mixed uniformly in a short time, and then poured into a suction filtration device; the ultrasonic power was 45 W and the time is 15 s;

(18) d) within 2 minutes, the mixture A was layered, and graphene was gradually transferred to the interface, and finally all of the graphene was confined at the interface; at the same time, graphene reaching the interface was spontaneously horizontally tiled and drifted freely under the action of interfacial shear force, and the (002) planes tended to be parallel to the interface, and at the same time, the graphene underwent highly oriented self-assembling;

(19) e) after the self-assembling was completed, a stable and uniform graphene film was formed at the interface as shown in FIG. 1; the graphene film was even and flat when viewed from the side and had a stable structure;

(20) f) the suction filtration device was activated, the solution was pumped out, the graphene film slowly at the interface descended as a whole and was finally completely attached to the surface of the filter paper;

(21) g) steps b)-f) were repeated, and 5 layers in total were subjected to suction filtration;

(22) h) the filter paper was dried at 60° C. for 12 hours to obtain a graphene film No. {circle around (1)} with graphene (002) planes parallel to each other at the microscopic level;

(23) i) 5 mL of the suspension obtained in step a) was taken out, the same suction filtration device was used for direct suction filtration to form a film, which was dried at 60° C. for 12 h to obtain a graphene film No. {circle around (2)}.

(24) The square resistances of graphene films with two different microstructures were measured, which was 3.34Ω/□ for {circle around (1)} and 10.04Ω/□ for {circle around (2)}. The result is as shown in FIG. 2, from which it can be seen that in this example, the square resistance of the graphene film of the present invention is reduced by two-thirds by adjusting the microstructure of the graphene film, thus significantly improving the electrical conductivity.

Example 2

(25) a) A electrically conductive and thermally conductive graphene (SE1233, Changzhou Sixth Element Materials Technology Co., Ltd.) was dispersed in water and subjected to ultrasonic treatment to form a stable suspension in a short time, and the graphene concentration was 1 mg/mL;

(26) b) 1 mL of the suspension prepared in step a) was taken out, water, alcohol and toluene were added therein, and the use amounts of the three liquids were adjusted to achieve a predetermined proper volume ratio of 2:1:4 to obtain a mixture A;

(27) c) the mixture A was ultrasonically oscillated to be mixed uniformly in a short time, and then poured into a suction filtration device; the ultrasonic power was 45 W and the time was 15 s;

(28) d) within 2 minutes, the mixture A was layered, and graphene was gradually transferred to the interface, and finally all of graphene was confined at the interface; at the same time, graphene reaching the interface spontaneously was horizontally tiled and drifted freely under the action of interfacial shear force, and the (002) planes tended to be parallel to the interface, and at the same time, the graphene underwent highly oriented self-assembling;

(29) e) after the self-assembling was completed, a stable and uniform graphene film was formed at the interface; the graphene film was even and flat when viewed from the side and had a stable structure;

(30) f) the suction filtration device was activated, the solution was pumped out, the graphene film at the interface slowly descended as a whole and was finally completely attached to the surface of the filter paper;

(31) g) steps b)-f) were repeated, and 5 layers in total were subjected to suction filtration;

(32) h) the filter paper was dried at 60° C. for 12 hours to obtain a graphene film No. {circle around (1)} with graphene (002) planes parallel to each other at the microscopic level;

(33) i) 5 mL of the suspension obtained in step a) was taken out, the same suction filtration device was used for direct suction filtration to form a film, which was dried at 60° C. for 12 h to obtain a graphene film No. {circle around (2)}.

(34) The square resistances of the graphene films with two different microstructures were measured, which was 26.24Ω/□ for {circle around (1)} and 42.15Ω/□ for {circle around (2)}. The result is shown in FIG. 2, from which it can be seen that in this example, the square resistance of the graphene film of the present invention is reduced by 40% by adjusting the microstructure of the graphene film, thus significantly improving the electrical conductivity.

(35) Referring to FIG. 3, a comparison diagram of the films obtained by an ordinary suction filtration method (a) and the method of the present invention (b) with the same amount of graphene shows that the coverage area of the film obtained by the method of the present invention is much larger than the film obtained by the ordinary suction filtration method, suggesting that the present invention has the effect of promoting graphene sheets to be tiled horizontally as much as possible (the 002 planes are parallel to each other).

(36) The above content is only to illustrate the technical concept of the present invention, and is not intended to limit the protection scope of the present invention. Any modification made on the basis of the technical solution according to the technical concept proposed by the present invention falls within the protection scope of the claims of the present invention.