CN111484002A

CN111484002A - Preparation method and application of porous graphene membrane

Info

Publication number: CN111484002A
Application number: CN202010305233.8A
Authority: CN
Inventors: 力小安; 嵇从民
Original assignee: Nanjing Momentum Material Technology Co ltd
Current assignee: Nanjing Momentum Material Technology Co ltd
Priority date: 2020-04-17
Filing date: 2020-04-17
Publication date: 2020-08-04
Anticipated expiration: 2040-04-17
Also published as: CN111484002B

Abstract

The invention discloses a preparation method and application of a porous graphene film, wherein graphene is generated by an in-situ method, under the condition of high temperature, a carbon precursor is firstly carbonized, then metal oxide is reduced into a simple substance by carbon, and then the metal catalyzes the carbon to become the graphene.

Description

Preparation method and application of porous graphene membrane

Technical Field

The invention relates to a graphene film, in particular to a preparation method and application of a porous graphene film; belongs to the technical field of carbon materials.

Background

Graphene (Graphene) is a polymer made of carbon atoms in sp²The hybrid tracks form a hexagonal honeycomb lattice two-dimensional carbon nanomaterial. Has excellent optical, electrical and mechanical properties, can be widely applied to a plurality of fields of mechanics, electricity, biology and the like, and particularly has wide application prospect in the field of nano materials.

In the prior art, in the preparation process of the graphene film, the main raw material is graphene oxide, but the cost of the graphene oxide is too high, so that the graphene film product lacks market competitiveness, cannot be widely popularized, and greatly limits the application field of the graphene film. For example, the invention patent "preparation method of heterostructure porous graphene oxide film, graphene film and generator" with application number 201810715882.8 discloses a preparation method of heterostructure porous graphene oxide film: firstly, carrying out freeze drying on a graphene oxide solution to prepare graphene oxide aerogel; then heating and reducing the graphene oxide aerogel from the bottom to obtain a partially reduced graphene oxide aerogel at the bottom; and finally, applying pressure to the graphene oxide aerogel with the partially reduced bottom in the vertical direction to obtain the heterostructure porous graphene oxide film. The method comprises the steps of carrying out freeze drying on a graphene oxide solution, heating and reducing the bottom of the graphene oxide solution, and vertically applying pressure to obtain the heterostructure porous graphene oxide film. However, as previously mentioned, the high cost of the raw materials and processes results in a product that is less competitive in the marketplace.

In view of this, there is a need to develop a new method for preparing a porous graphene film, so as to simplify the process and reduce the cost, thereby improving the market competitiveness of the product.

Disclosure of Invention

In order to solve the defects of the prior art, the invention aims to provide a preparation method and application of a porous graphene membrane.

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

the invention firstly discloses a preparation method of a porous graphene membrane, which comprises the following steps:

s1, preparing a precursor mixture: uniformly mixing a template agent, a carbon precursor and a solvent to prepare a precursor mixture; wherein the template agent is also a catalyst for catalyzing the formation of graphene;

s2, forming the mixture film layer prepared in the step S1 on the substrate;

s3, drying to remove the solvent in the mixture to form a embryonic membrane;

s4, catalyzing carbon in the carbon precursor in situ to generate graphene;

and S5, demolding to obtain the porous graphene film, wherein the thickness of the graphene film can be adjusted within the range of 100 nanometers to 1 centimeter according to needs.

The membrane obtained by the method comprises a three-dimensional porous open network which is connected with each other, and the pore diameter can be adjusted within the range of 2 nm-10 um.

Preferably, the carbon precursor is a substance capable of generating carbon at high temperature, and is selected from one or more of pitch, carbohydrate, and alcohol, preferably mesophase pitch, and is selected from naphthyl pitch, coal-based pitch, and petroleum-based pitch. The solvent is one of water, acetone or alcohol, the mass fraction of the solvent in the mixture is 40-90%, and the dosage of the solvent can be adjusted according to the consistency of the precursor mixture.

More preferably, the template is selected from one of inorganic particles of iron oxide, ferroferric oxide, nickel oxide and cobalt oxide, and in the subsequent high-temperature carbonization process of step S4, the oxide is reduced by carbon into elemental metal (carbon reduces the metal oxide into elemental metal), and the elemental metal catalyzes the carbon to be converted into graphene. It should be particularly noted that the templating agent should not react with the carbon precursor in the previous steps S1-S3.

Preferably, in step S4, the template is catalyzed by high temperature heat treatment to form graphene. The heat treatment temperature is 600-1000 ℃, and the heat treatment time is 1-24 h.

More preferably, in order to prevent the oxidation reaction from occurring, the heat treatment is performed in a protective atmosphere of nitrogen, helium, argon, or a mixed gas thereof.

Preferably, the template agent is ferric chloride and ammonia water, ferric hydroxide is generated in situ through a chemical reaction, ferric oxide is generated through subsequent pyrolysis, then carbon reduces metal oxide into a simple substance, and then the simple substance catalyzes the carbon to generate graphene.

Still preferably, the precursor mixture further contains a binder selected from one of PVA and a carbon source (glucose, sucrose, etc.). If PVA is used as the binder in this step, the carbon source may or may not be added, since PVA is also the carbon source.

Still more preferably, in step S5, an acid solution is used as the stripper, and the reaction generates hydrogen gas.

The invention also discloses application of the porous graphene membrane obtained by the preparation method, and the material can be applied to electrode materials or water treatment and has good market prospect.

The invention has the advantages that:

(1) in the preparation method of the porous graphene, the method for generating the graphene in situ is novel and unique, under the high-temperature condition, a carbon precursor is firstly carbonized, then the carbon reduces a metal oxide into a metal simple substance, and then the metal simple substance catalyzes the carbon to generate the graphene;

(2) the graphene film obtained by the preparation method has better conductivity and can be applied to electrode materials;

(3) in the high-temperature carbonization process, part of carbon atoms volatilize in a gaseous state during carbonization of organic components, the carbon atoms form graphene under the catalytic action of a template agent, and the carbon atoms volatilized in the gaseous state endow a product with a microscopically open three-dimensional network-shaped porous structure, so that the graphene film has a good application prospect in the application fields of water treatment and the like.

Drawings

Fig. 1 is an SEM image (2 μm) of a porous graphene film obtained by the preparation method of the present invention;

fig. 2 is an SEM image (20nm) of the porous graphene film obtained by the preparation method of the present invention.

Detailed Description

The invention is described in detail below with reference to the figures and the embodiments.

In the present invention, all the raw materials are commercially available unless otherwise specified.

Example 1

The graphene film obtained in the embodiment is a graphene film with a three-dimensional porous structure inside, and the preparation steps are as follows:

s1 preparation of precursor mixture

Uniformly mixing iron oxide, mesophase pitch and water to prepare a precursor mixture, wherein the weight ratio of the iron oxide to the mesophase pitch to the water is 3:3: 10.

S2, forming the mixture film layer prepared in the step S1 on the substrate, and preparing a uniform coating with adjustable thickness by a tape casting method or a coating method;

s3, drying to remove the solvent in the mixture to form a embryonic membrane, wherein the drying temperature is less than 50 ℃, and natural airing is preferred;

s4, catalyzing carbon in the carbon precursor in situ to generate graphene;

the method is a key step of the method, the graphene is generated in situ by a heat treatment method, the heat treatment temperature is 600-1000 ℃, and the heat treatment time is 1-24 h; specifically, in this example, the heat treatment temperature was 800 ℃ and the heat treatment time was 20 hours. And it should be noted that this step should be performed in a protective atmosphere, such as nitrogen, helium, argon, or a mixture thereof.

And S5, adopting an acetic acid solution as a stripping agent, stripping the template and drying to obtain the porous graphene film.

Through detection, the film thickness of the graphene film of the embodiment 1 is 100 μm, SEM images thereof are shown in fig. 1 and fig. 2, it is clear from the figures that the graphene film has a rich three-dimensional porous structure, and the pores therein have a micro-nano size and good conductivity.

Example 2

The preparation method of the embodiment is similar to that of the embodiment 1, the difference is mainly that the raw materials are different, and the specific preparation steps are as follows:

s1 preparation of precursor mixture

And uniformly mixing nickel oxide, mesophase pitch and acetone to prepare a precursor mixture, wherein the weight ratio of the nickel oxide to the mesophase pitch to the acetone is 4:3: 8.

S2, forming the mixture film layer prepared in the step S1 on the substrate;

s3, naturally airing to remove the solvent in the mixture to form a embryonic membrane;

s4, heating the embryonic membrane to 600 ℃ in a protective atmosphere, preserving heat for 10h, then heating to 900 ℃ and preserving heat for 10h, and catalyzing carbon in a carbon precursor in situ to generate graphene;

Through detection, the thickness of the graphene film is 80 microns, the graphene film has rich three-dimensional porous structures, holes in the graphene film are micro-nano-sized, and the conductivity is good.

Example 3

The preparation method of this example is similar to that of example 2, and the difference is mainly that different templates are used, and the specific preparation steps are as follows:

s1 preparation of precursor mixture

Uniformly mixing ferric chloride, ammonia water, mesophase pitch and acetone to prepare a precursor mixture, wherein the weight ratio of the four components is 3:3:3: 10.

S2, forming the mixture film layer prepared in the step S1 on the substrate by spin coating;

s4, heating the blank film to 1000 ℃ in a protective atmosphere, preserving heat for 15h, and catalyzing carbon in the carbon precursor in situ to generate graphene;

Through detection, the thickness of the graphene film is 100 microns, the graphene film has rich three-dimensional porous structures, holes in the graphene film are micro-nano-sized, and the conductivity is good.

Example 4

The preparation method of this example is similar to that of example 2, and mainly differs in that the precursor mixture further includes a binder, and the preparation steps are as follows:

s1 preparation of precursor mixture

Uniformly mixing iron oxide, mesophase pitch, PVA (polyvinyl alcohol) and water to prepare a precursor mixture, wherein the weight ratio of the four components is 3:3:3: 20.

S2, forming the mixture film layer prepared in the step S1 on the substrate through a casting method;

s3, drying in an oven at 30 ℃ to remove the solvent in the mixture to form a embryonic membrane;

s4, under the protective atmosphere, carrying out in-situ catalysis on carbon in the carbon precursor through a heat treatment process to generate graphene;

in this example, the heat treatment temperature was 600 ℃ and the heat treatment time was 24 hours.

Through detection, the thickness of the graphene film is 200 microns, the graphene film has a rich three-dimensional porous structure, holes in the graphene film are micro-nano-sized, and the conductivity is good.

In conclusion, in the preparation method of the porous graphene, the method for generating the graphene in situ is novel and unique, under the high-temperature condition, the carbon precursor is firstly carbonized, then the carbon reduces the metal oxide into a simple substance, and then the carbon is catalyzed to become the graphene. The obtained graphene film has good conductivity, can be applied to electrode materials, has a three-dimensional network-shaped porous structure inside, and has good application prospect in the field of water treatment.

The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It should be understood by those skilled in the art that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by using equivalent alternatives or equivalent variations fall within the scope of the present invention.

Claims

1. A method for preparing a porous graphene membrane is characterized by comprising the following steps:

s1, preparing a precursor mixture: uniformly mixing a template agent, a carbon precursor and a solvent to prepare a precursor mixture;

s2, forming the mixture film layer prepared in the step S1 on the substrate;

s3, removing the solvent in the mixture to form a embryonic membrane;

s4, catalyzing carbon in the carbon precursor to generate graphene;

and S5, demolding to obtain the porous graphene film.

2. The method of claim 1, wherein the carbon precursor is a substance capable of generating carbon, and is selected from one or more of pitch, carbohydrate, and alcohol.

3. The method of claim 1, wherein in step S4, the reduction product of the template catalyzes carbon to form graphene through high temperature thermal treatment.

4. The method according to claim 3, wherein the template is selected from one of iron oxide, ferroferric oxide, nickel oxide and cobalt oxide.

5. The method for preparing the holey graphene film according to claim 4, wherein the heat treatment temperature is 600 to 1000 ℃ and the heat treatment time is 1 to 24 hours.

6. The method for producing the holey graphene film according to claim 4, wherein the heat treatment is performed in a protective atmosphere, and the protective atmosphere is an atmosphere of nitrogen, helium, argon, or a mixed gas thereof.

7. The method for preparing the porous graphene film according to claim 2, wherein the template agent is ferric chloride and ammonia water, ferric hydroxide is generated in situ through a chemical reaction, ferric oxide is generated through subsequent pyrolysis and reduced into a metal simple substance by carbon, and the graphene is generated through catalysis of the carbon.

8. The method for preparing the holey graphene film according to any one of claims 1 to 7, wherein the precursor mixture further comprises a binder selected from one of PVA, glucose and sucrose.

9. The method for preparing a holey graphene film according to claim 8, wherein an acid solution is used as a mold-releasing agent in step S5.

10. The application of the porous graphene membrane obtained by the preparation method according to claim 1 in electrode materials or water treatment.