CN102557022B - Preparation method of graphene conductive foam - Google Patents

Abstract

The invention relates to a preparation method of graphene conductive foam. In the method of the present invention, graphite flakes are firstly added into concentrated sulfuric acid containing sodium nitrate, then potassium permanganate is added, and the temperature is kept at 35-40°C for 60-90 minutes; water is added under magnetic stirring, and the temperature is kept at 85-95°C for 60-90 minutes Add hydrogen peroxide with a mass content of 30%, filter after stirring, and obtain graphene oxide by ultrasonic separation after two dispersions and centrifugation; disperse the graphene oxide in the water of the foam, and coat the graphene oxide on the surface of the foam. After foaming, immerse in an aqueous solution containing a reducing agent to carry out a reduction reaction to obtain a conductive foam whose surface is coated with a graphene conductive layer. The method of the invention obtains the conductive foam by adsorbing the graphene conductive film on the surface of the foam, and the prepared conductive foam has the advantages of low density, high electrical conductivity, large specific surface area and low cost.

Description

Preparation method of graphene conductive foam

technical field

The invention belongs to the technical field of materials, and in particular relates to a preparation method of graphene conductive foam.

Background technique

Conductive foam is a conductive solid material with a large number of connected or disconnected bubbles evenly distributed inside. It is used in antistatic, electromagnetic shielding, gas-sensitive or pressure-sensitive sensors, sewage purification and other fields. The common preparation method of conductive foam is to fill the polymer with conductive substance carbon black and then prepare it by foaming process.

Graphene is a planar two-dimensional monoatomic layer carbon material, and is the hardest nanomaterial found so far. At room temperature, the electron mobility of graphene reaches 10 ⁶ cm ² V ^-1 s ^-1 , and the resistivity is about 10 ^-6 Ωcm, which is also The material with the lowest resistivity. These properties of graphene ensure that the foam prepared from graphene has a lower density and higher electrical conductivity than ordinary foam materials. Chemical vapor deposition can prepare small-sized graphene foams, but limited by the preparation method, graphene foams have not yet been mass-produced.

Contents of the invention

The object of the present invention is to provide a kind of preparation method of graphene conductive foam, this method utilizes the graphene of high conductivity and common insulating foam material compound, realizes the preparation of low density, high conductivity graphene conductive foam.

The method of the present invention uses flake graphite as a raw material and adopts a chemical oxidation method to prepare a graphene oxide material. The graphene oxide is coated on the surface of foams such as polyurethane, polystyrene or polyethylene through a padding process, and then the surface of the polyethylene foam is coated The graphene oxide is reduced to graphene, and the conductive foam coated with graphene on the surface of polyurethane and other foams is obtained.

The concrete steps of the inventive method are:

Step (1). Sodium nitrate is added in the concentrated sulfuric acid as reaction solution, and the mass content of sodium nitrate in the reaction solution is 1～2%; Then graphite sheet is added in the reaction solution, and the mass ratio of graphite sheet and reaction solution is 1: 80～100;

Step (2). Potassium permanganate is added to the reaction solution, and the temperature is raised to 35-40° C. and then incubated for 60-90 minutes; the mass ratio of the added potassium permanganate to the added graphite sheet is 6-10:1;

Step (3). Water is added while magnetic stirring is carried out to the reaction solution, and the temperature is raised to 85-95°C and then kept for 60-90 minutes; the mass ratio of the added water to the added graphite sheet is 350-400:1;

Step (4). Add hydrogen peroxide with a mass content of 30%, and filter after stirring for 5 to 10 minutes; the mass ratio of the added hydrogen peroxide to the added graphite sheet is 5 to 6:1;

Step (5). Disperse the filtered product with water, and then perform a centrifugal separation with a centrifuge at a rate of 1000 to 2000 rpm;

Step (6). Dispersing the product obtained by the primary centrifugation with water again, and then performing secondary centrifugation with a centrifuge at a rate of 8,000 to 10,000 rpm;

Step (7). Water is added to the product separated by secondary centrifugation, and ultrasonic separation is used to obtain graphene oxide;

Step (8). The foam is immersed in the water dispersed with graphene oxide obtained in step (7), and the graphene oxide is coated on the foam surface by a padding process; the mass ratio of added foam and graphite sheet is 1～20: 1;

Described foam is polyurethane foam, polystyrene foam, polyethylene foam, polyvinyl chloride foam or polypropylene foam;

Step (9). The foam coated with graphene oxide on the surface is fished out and immersed in an aqueous solution containing a reducing agent to carry out a reduction reaction to obtain a conductive foam coated with a graphene conductive layer on the surface; wherein the aqueous solution contains the reducing agent and graphite The mass ratio of the flakes is 2-10:1.

The reducing agent is hydrazine, dimethylhydrazine, sodium borohydride, lithium aluminum hydride, hydroiodic acid or hydrobromic acid.

The method of the invention obtains the conductive foam by adsorbing the graphene conductive film on the surface of the foam, and the prepared conductive foam has the advantages of low density, high electrical conductivity, large specific surface area and low cost. The conductive layer graphene on the surface of the foam will not fall off after repeated washing with water, and it can be used repeatedly as a filter material for filtering pollutants in environmental protection equipment after use. Compared with existing sensors, the new gas sensor made of graphene foam material can overcome the above shortcomings and play an important role in gas detection and environmental detection. effect. The graphene conductive foam prepared by the method of the invention has good mechanical strength and elasticity, and the resistance will change obviously under external forces such as extrusion and bending, and can be used to prepare new vibration sensors and the like.

Detailed ways

Example 1.

Step (1). 10 gram sodium nitrates are added in the concentrated sulfuric acid of 990 gram 98% as reaction liquid, then 10 gram graphite flakes are added in the reaction liquid;

Step (2). Slowly add 60 grams of potassium permanganate to the reaction solution, and keep warm for 90 minutes after the temperature rises to 35° C.;

Step (3). Add 4 liters of water to the reaction solution while stirring it magnetically, and heat it for 90 minutes after the temperature rises to 85°C;

Step (4). Add 50 grams of hydrogen peroxide with a mass content of 30%, and filter after stirring for 10 minutes;

Step (5). Disperse the filtered product with water, and then perform a centrifugal separation with a centrifuge at a speed of 1000 rpm;

Step (6). Dispersing the product obtained by the primary centrifugation with water again, and then performing secondary centrifugation with a centrifuge at a rate of 10,000 rpm;

Step (7). Water is added to the product separated by secondary centrifugation, and ultrasonic separation is used to obtain graphene oxide;

Step (8). 200 grams of polyurethane foam are immersed in the water dispersed with graphene oxide, and the graphene oxide is coated on the surface of the foam by padding process;

Step (9). After the polyurethane foam coated with graphene oxide on the surface is pulled out, it is immersed in an aqueous solution containing 20 grams of dimethylhydrazine to carry out a reduction reaction to obtain a conductive foam coated with a graphene conductive layer on the surface.

Example 2.

Step (1). 15 gram sodium nitrates are added in the concentrated sulfuric acid of 785 gram 98% as reaction solution, then 10 gram graphite flakes are added in the reaction solution;

Step (2). Slowly add 70 grams of potassium permanganate to the reaction solution, and keep warm for 70 minutes after the temperature rises to 37° C.;

Step (3). Add 3.5 liters of water to the reaction solution while stirring it magnetically, and heat it for 75 minutes after the temperature rises to 90°C;

Step (4). Add 60 grams of hydrogen peroxide with a mass content of 30%, and filter after stirring for 5 minutes;

Step (5). Disperse the filtered product with water, and then perform a centrifugal separation with a centrifuge at a speed of 1500 rpm;

Step (6). Dispersing the product obtained by primary centrifugation with water again, and then performing secondary centrifugation with a centrifuge at a rate of 5000 rpm;

Step (7). Water is added to the product separated by secondary centrifugation, and ultrasonic separation is used to obtain graphene oxide;

Step (8). 100 grams of polystyrene foam are immersed in the water dispersed with graphene oxide, and the graphene oxide is coated on the foam surface by a padding process;

Step (9). After the polystyrene foam coated with graphene oxide on the surface is pulled out, it is immersed in an aqueous solution containing 100 grams of sodium borohydride to carry out a reduction reaction to obtain a conductive foam coated with a graphene conductive layer on the surface.

Example 3.

Step (1). 18 gram sodium nitrates are added in the concentrated sulfuric acid of 882 gram 98% as reaction liquid, then 10 gram graphite flakes are added in the reaction liquid;

Step (2). Slowly add 80 grams of potassium permanganate to the reaction solution, and keep warm for 60 minutes after the temperature rises to 40° C.;

Step (3). Add 3.8 liters of water to the reaction solution while stirring it magnetically, and heat it for 60 minutes after the temperature rises to 95°C;

Step (4). Add 55 grams of hydrogen peroxide with a mass content of 30%, and filter after stirring for 8 minutes;

Step (5). Disperse the filtered product with water, then perform a centrifugation with a centrifuge at a speed of 2000 rpm;

Step (6). Dispersing the product obtained by primary centrifugation with water again, and then performing secondary centrifugation with a centrifuge at a rate of 8000 rpm;

Step (7). Water is added to the product separated by secondary centrifugation, and ultrasonic separation is used to obtain graphene oxide;

Step (8). 10 grams of polyethylene foam is immersed in the water that is dispersed with graphene oxide, and graphene oxide is coated on the foam surface by padding process;

Step (9). After the polyethylene foam whose surface is coated with graphene oxide is pulled out, it is immersed in an aqueous solution containing 50 grams of hydrazine to carry out a reduction reaction to obtain a conductive foam whose surface is coated with a graphene conductive layer.

Example 4.

Step (1). 15 gram sodium nitrates are added in the vitriol oil of 985 gram 98% as reaction solution, then 10 gram graphite flakes are added in the reaction solution;

Step (2). Slowly add 90 grams of potassium permanganate to the reaction solution, and keep warm for 75 minutes after the temperature rises to 35° C.;

Step (3). Add 3.6 liters of water to the reaction solution while stirring it magnetically, and heat it for 75 minutes after the temperature rises to 88°C;

Step (4). Add 57 grams of hydrogen peroxide with a mass content of 30%, and filter after stirring for 6 minutes;

Step (5). Disperse the filtered product with water, then perform a centrifugation with a centrifuge at a speed of 1200 rpm;

Step (6). Dispersing the product obtained by the primary centrifugation with water again, and then performing secondary centrifugation with a centrifuge at a rate of 10,000 rpm;

Step (7). Water is added to the product separated by secondary centrifugation, and ultrasonic separation is used to obtain graphene oxide;

Step (8). 50 grams of polypropylene foam are immersed in the water dispersed with graphene oxide, and graphene oxide is coated on the foam surface by padding process;

Step (9). After pulling out the polypropylene foam whose surface is coated with graphene oxide, it is immersed in an aqueous solution containing 40 grams of hydroiodic acid to carry out a reduction reaction to obtain a conductive foam whose surface is coated with a graphene conductive layer.

Example 5.

Step (1). 10 gram sodium nitrates are added in the concentrated sulfuric acid of 790 gram 98% as reaction liquid, then 10 gram graphite flakes are added in the reaction liquid;

Step (2). Slowly add 70 grams of potassium permanganate to the reaction solution, and keep warm for 70 minutes after the temperature rises to 40° C.;

Step (3). Add 3.9 liters of water to the reaction solution while stirring it magnetically, and heat it for 70 minutes after the temperature rises to 92°C;

Step (4). Add 52 grams of hydrogen peroxide with a mass content of 30%, and filter after stirring for 9 minutes;

Step (5). Disperse the filtered product with water, then perform a centrifugation with a centrifuge at a speed of 2000 rpm;

Step (6). Dispersing the product obtained by primary centrifugation with water again, and then performing secondary centrifugation with a centrifuge at a rate of 5000 rpm;

Step (7). Water is added to the product separated by secondary centrifugation, and ultrasonic separation is used to obtain graphene oxide;

Step (8). 150 grams of polyvinyl chloride foams are immersed in the water dispersed with graphene oxide, and graphene oxide is coated on the foam surface by padding process;

Step (9). After the polyvinyl chloride foam coated with graphene oxide on the surface is pulled out, it is immersed in an aqueous solution containing 80 grams of hydrobromic acid to carry out a reduction reaction to obtain a conductive foam coated with a graphene conductive layer on the surface.

Example 6.

Step (1). 10 gram sodium nitrates are added in the concentrated sulfuric acid of 890 gram 98% as reaction liquid, then 10 gram graphite flakes are added in the reaction liquid;

Step (2). Slowly add 100 grams of potassium permanganate to the reaction solution, and keep warm for 80 minutes after the temperature rises to 35° C.;

Step (3). Add 3.7 liters of water to the reaction solution while stirring it magnetically, and heat it for 80 minutes after the temperature rises to 85°C;

Step (4). Add 55 grams of hydrogen peroxide with a mass content of 30%, and filter after stirring for 7 minutes;

Step (5). Disperse the filtered product with water, and then perform a centrifugal separation with a centrifuge at a speed of 1800 rpm;

Step (6). Dispersing the product obtained by primary centrifugation with water again, and then performing secondary centrifugation with a centrifuge at a speed of 3000 rpm;

Step (7). Water is added to the product separated by secondary centrifugation, and ultrasonic separation is used to obtain graphene oxide;

Step (8). 20 grams of polyurethane foam are immersed in the water dispersed with graphene oxide, and graphene oxide is coated on the foam surface by padding process;

Step (9). After the polyurethane foam coated with graphene oxide on the surface is pulled out, it is immersed in an aqueous solution containing 30 grams of lithium aluminum hydride to carry out a reduction reaction to obtain a conductive foam coated with a graphene conductive layer on the surface.

Claims (3)

1. The preparation method of graphene conductive foam is characterized in that the concrete steps of the method are: Step (1). Sodium nitrate is added in the concentrated sulfuric acid as reaction solution, and the mass content of sodium nitrate in the reaction solution is 1～2%; Add graphite sheet in the reaction solution again, the mass ratio of graphite sheet and reaction solution is 1: 80～100; Step (2). Potassium permanganate is added to the reaction solution, and the temperature is raised to 35-40° C. and then incubated for 60-90 minutes; the mass ratio of the added potassium permanganate to the added graphite sheet is 6-10:1; Step (3). Water is added while magnetic stirring is carried out to the reaction solution, and the temperature is raised to 85-95°C and then kept for 60-90 minutes; the mass ratio of the added water to the added graphite sheet is 350-400:1; Step (4). Add hydrogen peroxide with a mass content of 30%, and filter after stirring for 5 to 10 minutes; the mass ratio of the added hydrogen peroxide to the added graphite sheet is 5 to 6:1; Step (5). Disperse the filtered product with water, and then perform a centrifugal separation with a centrifuge at a rate of 1000 to 2000 rpm; Step (6). Dispersing the product obtained by the primary centrifugation with water again, and then performing secondary centrifugation with a centrifuge at a rate of 8,000 to 10,000 rpm; Step (7). Water is added to the product separated by secondary centrifugation, and ultrasonic separation is used to obtain graphene oxide; Step (8). The foam is immersed in water dispersed with graphene oxide, and the graphene oxide is coated on the surface of the foam by a padding process; the mass ratio of the added foam to graphite flakes is 1 to 20:1; Step (9). The foam coated with graphene oxide on the surface is fished out and immersed in an aqueous solution containing a reducing agent to carry out a reduction reaction to obtain a conductive foam coated with a graphene conductive layer on the surface; wherein the aqueous solution contains the reducing agent and graphite The mass ratio of the flakes is 2-10:1. 2. the preparation method of graphene conductive foam as claimed in claim 1 is characterized in that: the foam described in step (8) is polyurethane foam, polystyrene foam, polyethylene foam, polyvinyl chloride foam or polypropylene foam Foam. 3. the preparation method of graphene conductive foam as claimed in claim 1 is characterized in that: the reducing agent described in step (9) is hydrazine, dimethylhydrazine, sodium borohydride, lithium aluminum hydride, hydroiodic acid or hydrobromic acid.