CN102815043B - Preparation method of grapheme and polyaniline composite paper, and products thereof - Google Patents

Abstract

The invention relates to a preparation method of graphene/polyaniline composite paper and products thereof. More specifically, the present invention provides a method for preparing graphene/polyaniline composite paper, comprising the steps of: providing a dispersion of graphene oxide; mixing the graphene oxide dispersion with a reducing agent to obtain a slurry, and then coating the slurry on a substrate, followed by drying to obtain a graphene paper; and obtaining a graphene/polyaniline composite paper by depositing polyaniline on the graphene paper. The advantage of the present invention is to utilize simple operation, make soft graphene paper with high electrical conductivity and high mechanical performance on a large scale, the graphene/polyaniline composite paper that this graphene paper is made as the substrate is used in supercapacitor electrode material The field has good application prospects.

Description

A kind of preparation method and product of graphene and polyaniline composite paper

technical field

The invention relates to the technical field of nanomaterials, and more particularly to a preparation method of graphene/polyaniline composite paper and its products.

Background technique

Supercapacitors have attracted increasing research interest as an electrochemical energy storage device. Graphene is a monoatomic layer structure with sp ² carbon atoms arranged in a hexagonal lattice. Due to its excellent properties such as high electronic conductivity, high mechanical strength, and large specific surface area, it has become a new and competitive electroactive material. electrode material. Polyaniline is a conductive polymer widely used as a pseudocapacitive material, which has the advantages of low cost, easy synthesis, environmental stability and large specific capacitance value. However, during charge and discharge, the swelling and shrinkage of polyaniline during the ion insertion and release process will destroy the polymer backbone, which greatly impairs its charge-discharge cycle life. Therefore, fully combining the advantages of graphene and polyaniline is a very scientific and promising idea for building a supercapacitor material with both high energy density and high power density.

From the domestic and foreign research trends of graphene/polyaniline composite materials, most of the research results focus on the preparation of powder composite materials. During the fabrication of electrodes, the use of binders such as thiophene greatly increases energy consumption in order to adhere the powder to the conductive substrate. Therefore, the preparation of self-supporting graphene/polyaniline macroscopic film materials or paper materials is not only convenient to use, but also overcomes the shortcomings caused by powder materials. At present, "American Nano" (ACS Nano, 2010, No. 4, 1963 pages) has reported that graphene/polyaniline composite paper is made by vacuum filtration of graphene and polyaniline mixed dispersion, but due to these two components The lack of real interaction between them makes the capacitance value of the electrode material low. Another work on the preparation of graphene/polyaniline composite paper reported by "American Nano" (ACS Nano, 2009, No. 3, page 1745) is to prepare graphene paper by vacuum filtration, and then use electricity to Polyaniline is electroplated by chemical polymerization, but the capacitance performance of the material is not high due to the general conductivity of the graphene paper prepared by vacuum filtration. In order to improve the practical application prospects of such materials as electrode materials, it is urgent to develop a cheap and convenient technical means to prepare a large amount of graphene/polyaniline composite paper with high capacitance performance.

Contents of the invention

The present invention mainly provides a preparation method of graphene/polyaniline composite paper aiming at the current limited technology.

For this reason, the invention provides a kind of preparation method of graphene/polyaniline composite paper, it is characterized in that, comprises the following steps:

a. Provide graphene oxide dispersion;

b. mixing the graphene oxide dispersion with a reducing agent to obtain a slurry, and then coating the slurry on a substrate, followed by drying to obtain a graphene paper; and

c. obtaining the graphene/polyaniline composite paper by depositing polyaniline on the graphene paper.

In a preferred embodiment, the graphene oxide dispersion is provided by the following steps:

a1. Add the mixture of graphene flakes and nitrates such as sodium nitrate or potassium nitrate to a strong acid such as concentrated sulfuric acid and concentrated nitric acid for pre-oxidation, and stir to obtain a dispersion;

a2. Add a strong oxidizing agent such as potassium permanganate to the dispersion of a1, stir, and leave for 1-10 days to obtain a brown-gray paste;

a3. Add deionized water and hydrogen peroxide successively to the brown-gray paste of a2 to obtain a bright yellow dispersion;

a4. centrifuging, washing and dialysis the bright yellow dispersion in a3 to obtain the graphene oxide dispersion.

In a preferred embodiment, the reducing agent in step b is hydroiodic acid, hydrazine hydrate or sodium borohydride.

In a preferred embodiment, an aqueous solution of hydriodic acid is used as a reducing agent in the step b, and the volume ratio of the graphene oxide dispersion to the aqueous solution of hydriodic acid is (10-5):1.

In a preferred embodiment, the substrate in step b is Teflon (or polytetrafluoroethylene).

In a preferred embodiment, the drying temperature in step b is 60-90°C.

In a preferred embodiment, the drying time in step b is 1-8 hours.

In a preferred embodiment, the step b also includes washing and drying the graphene paper on the substrate after drying with water and alcohol (such as ethanol) in sequence, thereby obtaining from the substrate Complete graphene paper.

In a preferred embodiment, in the step c, polyaniline is electroplated and deposited on the graphene paper by electrochemically polymerizing aniline monomers, thereby forming the graphene/polyaniline composite paper.

In a preferred embodiment, the electroplating deposition is achieved through the following steps:

c1. prepare 1 mol/liter of sulfuric acid solution in water and ethanol mixed solvent;

c2. adding aniline monomer to the mixed solution obtained in step c1; and

c3. Carry out electrochemical polymerization with a three-electrode method, wherein the graphene paper is used as a working electrode, a platinum electrode is used as a counter electrode, silver/silver chloride is used as a reference electrode, and the mixed solution obtained in step c2 is used as an electrolyte .

In a preferred embodiment, the volume ratio of water and ethanol in the mixed solvent of water and ethanol is (1-10):1.

In a preferred embodiment, an aniline solution with a concentration of 0.05-0.5 mol/liter is used.

In a preferred embodiment, the operating voltage during the electrochemical polymerization is 0.8 volts.

In a preferred embodiment, the electrochemical polymerization takes 2 to 30 minutes.

In addition, the present invention provides a graphene/polyaniline composite paper obtained by the above preparation method.

The method provided by the invention has the advantages of simple steps, easy operation, economy and speed, and the prepared graphene/polyaniline composite paper has the advantages of high electrical conductivity, good mechanical properties and easy processing.

Description of drawings

Fig. 1 is the scanning electron micrograph of the graphene/polyaniline composite paper prepared according to the embodiment of the present invention 1;

Fig. 2 is the scanning electron micrograph of the graphene/polyaniline composite paper prepared according to the embodiment of the present invention 2;

Fig. 3 is the scanning electron micrograph of the graphene/polyaniline composite paper prepared according to the embodiment of the present invention 3;

Fig. 4 is the scanning electron micrograph of the graphene/polyaniline composite paper prepared according to the embodiment of the present invention 4; With

Fig. 5 is the charge and discharge measurement curve of the graphene/polyaniline composite paper prepared according to Example 1 of the present invention.

Detailed ways

The invention provides a kind of preparation method of graphene/polyaniline composite paper, concrete steps: at first provide a kind of dispersion liquid of graphene oxide, then this graphene oxide dispersion liquid and reducing agent such as hydroiodic acid, hydrazine hydrate or boron Sodium hydride mixed slurry is spread on such as Teflon substrate, dried and torn off to obtain graphene paper, and finally, for example, electrochemical polymerization is used to deposit polyaniline on the graphene paper to obtain graphene/polyaniline composite Paper.

More preferably, the preparation method of a kind of graphene/polyaniline composite paper of the present invention, comprises the following steps:

a. providing a graphene oxide dispersion;

b. Evenly spread the mixed slurry of graphene oxide and reducing agent such as hydroiodic acid on a Teflon substrate, place it in a drying device such as an oven, and take it out after drying;

Optionally, the dried graphene paper on the substrate is washed successively with water and alcohol (such as ethanol) multiple times, and for example, dried at room temperature to tear off the complete graphene paper from the substrate;

c. The aniline monomer is polymerized by means of electrochemical polymerization and electroplated and deposited on the above-mentioned graphene paper to obtain a graphene/polyaniline composite paper.

Preferably, above-mentioned step a comprises steps:

a1. adding the mixture of graphene flakes and nitrates such as sodium nitrate or potassium nitrate to a strong acid such as concentrated sulfuric acid or concentrated nitric acid for pre-oxidation, stirring;

a2. Slowly add a strong oxidizing agent such as potassium permanganate to the dispersion of a1, stir, and place for 1-10 days;

a3. add deionized water and hydrogen peroxide successively to the mixture obtained in a2;

a4. The graphene oxide dispersion is obtained after repeated centrifugal washing and dialysis.

Preferably, an aqueous solution of hydroiodic acid is used as a reducing agent in the above step b, and the volume ratio of the graphene oxide dispersion to the aqueous solution of hydroiodic acid is (10-5):1.

Preferably, the drying temperature in the above step b is 60-90°C.

Preferably, the drying time in the above step b is 1-8 hours.

In the optional step of the above step b, the size and shape of the prepared graphene paper is changed with the change of the Teflon substrate.

Preferably, the above step c includes steps:

c1. prepare the sulfuric acid solution of 0.5-2 mol/liter in water and ethanol mixed solvent;

c2. adding the aniline monomer to the mixed solution of c1 above;

c3. Carry out electrochemical polymerization with a three-electrode method, wherein graphene paper is used as a working electrode, a platinum electrode is a counter electrode, silver/silver chloride is a reference electrode, and the above c2 solution is used as an electrolyte to prepare graphene/polyaniline Composite paper.

Preferably, the volume ratio of water and ethanol in the above step c1 is (1-10): 1.

Preferably, the aniline monomer solution with a concentration of 0.05-0.5 mol/liter is used in the above step c2.

Preferably, the operating voltage of the electrochemical polymerization in step c3 above is 0.8 volts.

Preferably, the electrochemical polymerization time in the above step c3 is 2-30 minutes.

The advantage of the present invention is to use simple operation to prepare soft graphene paper with high electrical conductivity and mechanical properties in one step and in large quantities, and the graphene/polyaniline composite paper prepared on the basis of this graphene paper is used in supercapacitor electrodes. The field of materials has good application prospects.

The specific implementation manner of the present invention will be further described in detail below in conjunction with the examples. The following examples are intended to further illustrate the present invention, but are not intended to limit the scope of the present invention.

Example 1

(1) Preparation of graphene oxide dispersion: under the situation of constant stirring, 5 grams of graphite flakes and 3.75 grams of NaNO ₃ were added in 150 milliliters of concentrated sulfuric acid (98%), and the reactants were mixed and cooled in an ice bath; After stirring for half an hour, add 20 grams of KMnO ₄ to the above dispersion within half an hour; then remove the ice bath, the temperature of the suspension will rise back to about 35°C, and continue stirring for 20 hours to turn into a brown-gray paste; Afterwards, the stirring was stopped, and after standing for 5 days, 500 milliliters of deionized water and 30 milliliters of H ₂ O ₂ were added slowly while stirring successively to form a bright yellow suspension; Then add water to disperse the precipitate, repeat this process three times, and wash away the residual metal ions; then, add water to disperse the obtained precipitate, centrifuge, collect the upper layer of centrifugate, continue to add water to the lower layer of precipitation, collect the upper layer of centrifuge, and so on, until The upper layer of centrifugate was clear, and the lower layer was discarded. The collected supernatants were combined, and then dialyzed with a dialysis bag with a molecular weight of ^8,000-14,000 . The resulting product was characterized by Raman spectroscopy ^. The characteristic peak of the G band at the position shows that a uniform dispersion of graphene oxide has been obtained. A homogeneous dispersion of graphene oxide was obtained.

(2) After uniformly mixing the 5 mg/ml graphene oxide dispersion with hydroiodic acid at a volume ratio of 10:1, spread the obtained slurry on a Teflon substrate, and put it into a 90°C oven for 2 hours After that, take it out and let it cool down at room temperature.

(3) Add ethanol to the substrate covered with graphene paper, wash it several times, dry it, tear off the graphene paper from the substrate, and cut it into small pieces for later use.

(4) Preparation of graphene/polyaniline composite paper: configure 1 mol/liter of sulfuric acid solution in water and ethanol mixed solvent with a volume ratio of 1:1, then add aniline therein to obtain 0.1 mol/liter of aniline solution , with this solution as the electrolyte, the graphene paper prepared above is used as the working electrode, the platinum electrode is used as the counter electrode, and the silver/silver chloride electrode is used as the reference electrode. Under a constant voltage of 0.8 volts, electrochemical polymerization 10 Minutes, and carried out the Raman spectroscopic characterization of the obtained soft composite paper, in the spectrogram there appeared corresponding to ^phenazine , quinone hydrocarbon vibration, quinone hydrocarbon bending The characteristic peaks of vibration and carbon-hydrogen vibration of benzene ring are located at 1326, 1583 and 1619cm ^-1 corresponding to semiquinone group vibration, quinone carbon-carbon double construction vibration and carbon-carbon single bond vibration, and at 1481-1509cm ^-1 The quinoid carbon-nitrogen double-construction vibration and the polarized carbon-nitrogen single bond vibration at 1259 cm ^-1 , these results indicate that the obtained product is a graphene/polyaniline composite paper. Fig. 1 is the scanning electron micrograph of the graphene/polyaniline composite paper prepared according to the present embodiment, and it can be seen from the scanning electron micrograph shown in Fig. 1 that uniform polyaniline nanorods grow on the graphene paper.

Example 2

Repeat Example 1, with the following differences: when electrochemically polymerizing polyaniline on graphene paper, the electrolyte contains 0.05 mol/liter of aniline monomer. Fig. 2 is the scanning electron micrograph of the graphene/polyaniline composite paper obtained in the present embodiment 2, as can be seen from Fig. 2, the polyaniline particle of a thin layer grows on the graphene paper. Comparing with the scanning electron micrograph (see Fig. 1 ) displayed by the composite paper prepared in Example 1, it can be seen that the microstructure of the composite paper is related to the concentration of aniline.

Example 3

Repeat embodiment 1, have following difference: when electrochemically polymerizing polyaniline on graphene paper, electrochemical polymerization time is 5 minutes, and Fig. 3 is the scanning electron microscope of the graphene/polyaniline composite paper that present embodiment 3 obtains Photo, the result is similar to Example 1, but because the polymerization time is slightly shorter, there are fewer polyaniline nanorods grown.

Example 4

Repeat Example 1 with the following difference: when polyaniline is electrochemically polymerized on graphene paper, the electrochemical polymerization time is 20 minutes. Fig. 4 is the scanning electron micrograph of the graphene/polyaniline composite paper that present embodiment 4 obtains, as can be seen from Fig. 4, along with the increase of electrochemical polymerization time, polyaniline nanorod grows denser, and with The growth density of polyaniline nanorods increases, and the color of the obtained graphene/polyaniline composite paper also changes accordingly.

Example 5

Repeat Example 1, with the following differences: in the preparation step of graphene/polyaniline composite paper, the sulfuric acid solution of 1 mol/liter is configured in the water and ethanol mixed solvent with a volume ratio of 5:1. The results were similar to Example 1.

Example 6

Repeat Example 1, with the following differences: in the preparation step of graphene/polyaniline composite paper, the sulfuric acid solution of 0.5 mol/liter is configured in the water and ethanol mixed solvent with a volume ratio of 10:1. The results were similar to Example 1.

Example 7

Repeat embodiment 1, following difference is arranged: after the graphene oxide dispersion liquid of 5 mg/ml is uniformly mixed with hydroiodic acid with the volume ratio of 5: 1, the slurry that obtains is laid on the teflon substrate, puts After reacting in an oven at 90°C for 2 hours, take it out and cool it at room temperature. The results were similar to Example 1.

Example 8

Repeat embodiment 1, following difference is arranged: after the graphene oxide dispersion liquid of 5 mg/ml and hydroiodic acid are mixed uniformly with the volume ratio of 10:1, the slurry that obtains is spread on the Teflon substrate, puts After reacting in a 60°C oven for 5 hours, take it out and cool it down at room temperature. The results were similar to Example 1.

Example 9

Repeat Example 1, with the following differences: after the graphene oxide dispersion of 5 mg/ml is uniformly mixed with hydrazine hydrate at a volume ratio of 10:1, the slurry obtained is spread on the Teflon substrate and placed in After reacting in an oven at 90°C for 2 hours, take it out and cool it down at room temperature. The results were similar to Example 1.

Example 10

Repeat Example 1, with the following differences: after the graphene oxide dispersion of 5 mg/ml and the sodium borohydride solution of 1 mol/liter are uniformly mixed with a volume ratio of 10:1, the slurry obtained is spread on Teflon On the dragon substrate, put it into a 90°C oven to react for 2 hours, take it out, and cool it at room temperature. The results were similar to Example 1.

In addition, the graphene/polyaniline composite paper prepared by the preparation method of graphene/polyaniline composite paper of the present invention has been measured as the performance of the electrode material of supercapacitor, and the results are shown in the charge and discharge (time) shown in Figure 5 -voltage) curve, as can be seen from Figure 5, its capacitance value can reach 753F/g, therefore, the graphene/polyaniline composite paper prepared by the present invention has excellent electrical properties.

It should be pointed out that the above descriptions are only preferred embodiments of the present invention, and for those skilled in the art, various modifications or transformations to these embodiments can be realized without departing from the technical principle and scope of the present invention, and These modifications should also be considered within the protection scope of the present invention.

Claims (13)

1. a preparation method of graphene/polyaniline composite paper, is characterized in that, comprises the following steps: a. Provide graphene oxide dispersion; b. mixing the graphene oxide dispersion with a reducing agent to obtain a slurry, and then coating the slurry on a substrate, followed by drying to obtain a graphene paper; and c. obtaining the graphene/polyaniline composite paper by depositing polyaniline on the graphene paper, Wherein the reducing agent used in the step b is hydroiodic acid, hydrazine hydrate or sodium borohydride, and the drying temperature in the step b is 60-90°C. 2. the preparation method of graphene/polyaniline composite paper according to claim 1, is characterized in that, described graphene oxide dispersion is provided by the following steps: a1. Add the mixture of graphite flakes and nitrates to a strong acid for pre-oxidation, and stir to obtain a dispersion; a2. Add a strong oxidizing agent to the dispersion of a1, stir, and place for 1-10 days to obtain a brown-gray paste; a3. Add deionized water and hydrogen peroxide successively to the brown-gray paste of a2 to obtain a bright yellow suspension; a4. centrifuging, washing and dialysis the bright yellow suspension in a3 to obtain the graphene oxide dispersion. 3. the preparation method of graphene/polyaniline composite paper according to claim 1, is characterized in that, uses hydroiodic acid aqueous solution as reducing agent in the described step b, and described graphene oxide dispersion liquid and described hydrogen The volume ratio of the iodic acid aqueous solution is (10-5):1. 4. the preparation method of graphene/polyaniline composite paper according to claim 1 is characterized in that, the substrate in the described step b is Teflon. 5. The preparation method of graphene/polyaniline composite paper according to claim 1, characterized in that, the drying time in the step b is 1 to 8 hours. 6. the preparation method of graphene/polyaniline composite paper according to claim 1 is characterized in that, in described step b, also comprises water and alcohol successively to the graphene paper on the substrate after drying Washed and dried to obtain a complete graphene paper from the substrate. 7. the preparation method of graphene/polyaniline composite paper according to claim 1, is characterized in that, in described step c, polyaniline is electroplated and deposited on described graphene paper by electrochemical polymerization aniline monomer , thereby forming the graphene/polyaniline composite paper. 8. the preparation method of graphene/polyaniline composite paper according to claim 7, is characterized in that, described electroplating deposition realizes by the following steps: c1. prepare the sulfuric acid solution of 0.5-2 mol/liter in water and ethanol mixed solvent; c2. adding the aniline monomer to the mixed solution obtained in step c1; c3. Carry out electrochemical polymerization with a three-electrode method, wherein the graphene paper is used as a working electrode, a platinum electrode is used as a counter electrode, silver/silver chloride is used as a reference electrode, and the mixed solution obtained in step c2 is used as an electrolyte . 9. the preparation method of Graphene/polyaniline composite paper according to claim 8, is characterized in that, the volume ratio of the water and ethanol in described water and ethanol mixed solvent is (1-10):1. 10. The preparation method of graphene/polyaniline composite paper according to claim 8, characterized in that, the use concentration is an aniline monomer solution of 0.05 to 0.5 mol/liter. 11. the preparation method of graphene/polyaniline composite paper according to claim 8 is characterized in that, the operating voltage in the described electrochemical polymerization process is 0.8 volts. 12. The preparation method of graphene/polyaniline composite paper according to claim 8, characterized in that, the electrochemical polymerization time is 2 to 30 minutes. 13. A graphene/polyaniline composite paper obtained by the preparation method described in any one of claims 1-12.