CN107937995B

CN107937995B - Graphene conductive film and preparation method thereof

Info

Publication number: CN107937995B
Application number: CN201711171612.7A
Authority: CN
Inventors: 代云茜; 符婉琳; 周洁; 马榕蔚; 黄依洋; 孙岳明
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2017-11-22
Filing date: 2017-11-22
Publication date: 2020-04-21
Anticipated expiration: 2037-11-22
Also published as: CN107937995A

Abstract

Mixing graphite powder and sodium chloride, washing with water to remove the sodium chloride, drying, adding concentrated sulfuric acid, stirring overnight, adding potassium permanganate into the solution, keeping the temperature not to exceed 20 ℃, heating to 40 ℃, heating to 90 ℃, adding ultrapure water, adding hydrogen peroxide, pickling with hydrochloric acid solution once, and dialyzing in distilled water to obtain high-concentration graphene oxide; and (3) wrapping the flexible substrate on a grounded metal roller through an electrostatic spinning machine to be used as a receiver to collect micro liquid drops obtained by electrospray, so as to form the graphene conductive film. The invention can form a flexible conductive film which can be bent at will; through simple hot-pressing treatment, the graphene-based composite membrane can be converted into a high-conductivity reduced graphene oxide composite membrane under the non-toxic and harmless conditions.

Description

Graphene conductive film and preparation method thereof

Technical Field

The invention belongs to a preparation technology of a nano-material composite film, and particularly relates to a graphene conductive film and a preparation method thereof.

Background

Due to the good strength, flexibility, electric conductivity, heat conductivity and optical characteristics of graphene, the graphene is greatly developed in the fields of physics, materials science, electronic information, computers, aerospace and the like. In recent years, the formation of graphene as a two-dimensional conductive thin film has become a hot spot in the field. Chemical Vapor Deposition (CVD) is currently the most efficient method for producing graphene thin films. The graphene film is prepared by vapor deposition by using carbon-containing organic gas as a raw material, and the graphene prepared by the method has the characteristics of large area and high quality, but the cost is higher at the present stage, and the process conditions need to be further improved. The graphene conductive film can be rapidly prepared by an electrostatic spraying method, and meanwhile, the substrate selection range is wide, and the thickness, the area and the shape of the graphene film can be regulated and controlled. Therefore, the method can be one of convenient methods for preparing the diversified graphene conductive films with high efficiency and low cost.

Disclosure of Invention

The technical problem to be solved is as follows: the invention provides a graphene conductive film and a preparation method thereof aiming at the technical problems, and the prepared flexible conductive film can be bent and cut at will.

The technical scheme is as follows: a preparation method of a graphene conductive film comprises the following preparation steps: mixing graphite powder and sodium chloride in a mass ratio of 10:1-30:1 according to a ratio, washing with water to remove the sodium chloride, drying, adding 20-25mL of concentrated sulfuric acid, stirring overnight, adding potassium permanganate into the solution according to a mass fraction of 20-30%, keeping the temperature at the moment not to exceed 20 ℃, then heating to 40 ℃ for 30min, finally heating to 90 ℃ for 45min, adding 18M omega ultrapure water to dilute the sulfuric acid concentration to 30-40 vol%, adding 150mL of 5-10 vol% hydrogen peroxide after 25min, pickling with a hydrochloric acid solution, dialyzing in distilled water for 3 days to obtain high-concentration graphene oxide; wrapping a flexible substrate on a grounding metal roller as a receiver to collect micro liquid drops obtained by electric spraying by using a NAON-01A electrostatic spinning machine under the conditions of voltage of 10kV-20kV, distance between a metal needle and a filament collector of 12-15cm, flow rate of 0.5-3mL/h and strand rotation speed of 500-3000rpm/min to form the graphene conductive film.

Preferably, the flexible substrate is 80g double glue a4 paper.

Preferably, the concentration of the hydrogen peroxide is 10 vol.%, and the concentration of the hydrochloric acid solution is 5 wt.%.

Preferably, sodium chloride is added into the dialyzed high-concentration graphene oxide, and the mass concentration of the sodium chloride is controlled to be 20-50%.

The graphene conductive film prepared by the preparation method.

The graphene composite film can be rapidly reduced into a reduced graphene oxide composite film through hot pressing (50-100 ℃), and the conductivity is greatly improved. The thickness and the conductivity of the film can be tested by the step instrument through the four-probe sheet resistance instrument. After 1000 bends, 95% of the initial conductivity was still maintained.

Has the advantages that: by regulating and controlling the flow speed, distance, voltage and time in the electrostatic spraying process, the viscosity of the electric spraying solution and the flexible substrate, composite conductive films with different thicknesses and different compositions can be obtained; by utilizing electrostatic spraying, the conductive film can be quickly and uniformly prepared; the flexible conductive film which can be bent at will can be formed by utilizing the flexibility of the substrate and the interaction between the graphene and the substrate (particularly, A4 paper-like materials can be tightly combined with graphene hydrogel through capillary action); through simple hot-pressing treatment, the graphene-based composite membrane can be converted into a high-conductivity reduced graphene oxide composite membrane under the non-toxic and harmless conditions.

Drawings

FIG. 1 is a SEM image of a cross section of a graphene sheet peeled off from a reduced graphene oxide/A4 paper;

FIG. 2 is a schematic view of a preparation process.

Detailed Description

The following examples are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Example 1:

a. preparing a graphene/A4 paper composite film by adopting an electrostatic spraying method:

firstly, preparing high-concentration graphene oxide by a modified Hummers method: mixing 1g of graphite powder and 0.05g of sodium chloride, washing with water to remove the sodium chloride, drying, adding 23mL of concentrated sulfuric acid, stirring for 22h, adding 6g of potassium permanganate into the solution, keeping the temperature at the moment not to exceed 20 ℃, subsequently heating to 40 ℃ for 30min, finally heating to 90 ℃ for 45min, adding 46mL of 18M omega ultrapure water, adding 140mL of distilled water and 10mL of 30 vol.% of hydrogen peroxide after 25min, pickling with 5 wt.% hydrochloric acid solution once, and dialyzing in the distilled water for 3 days to obtain the high-concentration graphene oxide.

And secondly, adding sodium chloride, controlling the mass concentration of the sodium chloride to be 30 wt%, and improving the viscosity of the graphene hydrogel through flocculation.

High-viscosity graphene oxide is used as an electric spraying solution, and a flexible substrate such as 80g of double-glue A4 paper is wrapped on a grounded metal roller to be used as a receiver to collect tiny liquid drops obtained by electric spraying under the conditions that the voltage is 10kV-20kV, the distance between a metal needle and a wire collector is 12.5cm, the flow rate is 0.5-3mL/h, and the strand rotating speed is 500-3000rpm/min, so that a composite film material is formed.

b. And (3) testing the conductivity:

and testing the sheet resistance R of the graphene/A4 paper composite film by adopting an SDY-5 type double-electric-test four-probe tester. And testing the thickness d of the graphene/A4 paper composite film by using a DEKTAK150 type step profiler. The conductivity rho of the graphene/A4 paper composite film is 1860S/m calculated through the formula (1).

ρ＝1/(R×d) (1)

Example 2:

b. Hot-pressing reduction:

and preparing the reduced graphene oxide/A4 paper composite membrane by hot pressing treatment at the temperature of 100 ℃.

c. And (3) testing the conductivity:

and testing the sheet resistance R of the graphene/A4 paper composite film by adopting an SDY-5 type double-electric-test four-probe tester. And testing the thickness d of the graphene/A4 paper composite film by using a DEKTAK150 type step profiler. The conductivity rho of the graphene/A4 paper composite film is 3670S/m through calculation of a formula (1).

ρ＝1/(R×d) (1)

Example 3:

b. Hot-pressing reduction:

c. Bending test

And (3) bending the reduced graphene oxide/A4 paper composite membrane 1000 times (bending angle is random).

d. And (3) testing the conductivity:

and testing the sheet resistance R of the reduced graphene oxide/A4 paper composite film by adopting an SDY-5 type double-electrical-test four-probe tester. And testing the thickness d of the reduced graphene oxide/A4 paper composite membrane by adopting a DEKTAK150 type step profiler. The conductivity rho of the reduced graphene oxide/A4 paper composite film is 3487S/m calculated by the formula (1).

ρ＝1/(R×d) (1)

TABLE 1 comparison table of film thickness, sheet resistance and conductivity of graphene/A4 paper

Claims

1. A preparation method of a graphene conductive film is characterized by comprising the following preparation steps: mixing graphite powder and sodium chloride according to a mass ratio of 10:1-30:1, washing with water to remove the sodium chloride, drying, adding 20-25mL of concentrated sulfuric acid, stirring overnight, adding potassium permanganate according to a mass fraction of 20-30%, keeping the temperature at the moment not to exceed 20 ℃, heating to 40 ℃ for 30min, finally heating to 90 ℃ for 45min, adding 18M omega ultrapure water to dilute the sulfuric acid to 30-40 vol%, adding 150mL of 5-10 vol% hydrogen peroxide after 25min, pickling with a hydrochloric acid solution, dialyzing in distilled water for 3 days to obtain high-concentration graphene oxide; wrapping a flexible substrate on a grounding metal roller as a receiver to collect micro liquid drops obtained by electric spraying by using a NAON-01A electrostatic spinning machine under the conditions that the voltage is 10kV-20kV, the distance between a metal needle and a filament collector is 12-15cm, the flow rate is 0.5-3mL/h, and the rotating drum rotating speed of the electrostatic spinning machine is 500-3000rpm, and forming the graphene conductive film.

2. The method of claim 1, wherein the flexible substrate is 80g double-coated A4 paper.

3. The method for preparing a graphene conductive film according to claim 1, wherein the concentration of the hydrogen peroxide is 10 vol.%, and the concentration of the hydrochloric acid solution is 5 wt.%.

4. The method for preparing a graphene conductive film according to claim 1, wherein sodium chloride is added to the dialyzed high-concentration graphene oxide, and the mass concentration of the sodium chloride is controlled to be 20% to 50%.

5. A graphene conductive film obtained by the preparation method according to any one of claims 1 to 4.