Conductive Polymer and Edge-Oxidized Graphene Thermoelectric Composite

Abstract

The present invention discloses a conductive polymer and edge-oxidized graphene thermoelectric composite material, comprising 0.1 to 99.9 wt% of a conductive polymer and 0.1 to 99.9 wt% of edge-oxidized graphene, based on the total weight of the conductive polymer and edge-oxidized graphene organic composite thermoelectric material being 100 wt%. The conductive polymer and edge-oxidized graphene thermoelectric composite material provided by the present invention selects edge-oxidized graphene and an organic conductive polymer for composite preparation of a thermoelectric material. Compared with the existing organic composite thermoelectric materials, the conductive polymer and edge-oxidized graphene thermoelectric composite material of the present invention forms a composite material with a large phase interface, a small-scale microstructure, and dispersed nanoparticles by introducing a nano two-phase, namely edge-oxidized graphene, into the organic conductive polymer. At the same time, by utilizing the inherently low thermal conductivity of the organic polymer, the electrical conductivity of the thermoelectric material is improved on the basis of the existing preparation technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic thermoelectric materials, and particularly relates to a thermoelectric composite material of a conductive polymer and edge-oxidized graphene. Background Art

[0002] As a new type of green functional material, thermoelectric materials utilize the movement of carriers inside solids to directly convert thermal energy and electrical energy into each other. Common thermoelectric materials are mainly inorganic materials (such as Bi2Te3, PbTe, GeTe, etc.). Most inorganic thermoelectric materials contain expensive heavy metals, and they have disadvantages such as poor flexibility and processability, thus resulting in problems such as high costs and environmental pollution, and also restricting their applications in the field of flexible wearable thermoelectric power generation. Organics, especially polymers, are usually composed of light elements such as C, H, O, etc.; their synthesis redox reactions are usually carried out in solvents, and the experimental equipment is easy to operate, having the advantages of low costs in terms of raw materials and manufacturing. Compared with traditional inorganic substances, organics also have special advantages in terms of costs, safety, processability, etc. However, the electrical transport performance of organics is relatively low, thus restricting their applications in the thermoelectric field.

[0003] Subsequently, researchers found that adding different inorganic substances is an effective way to improve the thermoelectric performance of organic materials. By compounding inorganic nanoparticles with high electrical conductivity and conductive polyaniline with low thermal conductivity, the synergistic effect of the two is utilized to improve the electrical conductivity while increasing the Seebeck coefficient of the material through the interfacial energy filtering effect, and the phonon interfacial scattering effect generated by the nano second phase is used to reduce the thermal conductivity, thereby effectively improving the thermoelectric performance of organics.

[0004] Due to the high carrier mobility, low density, good flexibility, and high surface area of graphene, it is often used to compound with organic polymers to obtain thermoelectric materials with excellent electrical conductivity. However, its disadvantages such as hydrophobicity and poor dispersibility result in less improvement in the thermoelectric performance of the composite material. Although graphene oxide (GO) after oxidation treatment has hydrophilicity, there are many internal oxidation sites and poor electrical properties, which to a certain extent restricts the practical application of graphene. Compared with graphene oxide, for edge-oxidized graphene, the SP 2 hybrid structure of its carbon basal plane is not damaged, only a small amount of oxygen-containing functional groups are modified on the edge of graphene, with few internal defects, and the conjugated structure of graphene can be retained to the greatest extent; at the same time, compared with graphene and graphene oxide, edge-oxidized graphene has the advantages of being hydrophilic, easy to disperse, capable of bonding with organics, and maintaining good electrical properties.

[0005] Currently, there is no literature report in the prior art on applying the composite material of edge-oxidized graphene and organic conductive polymer to the thermoelectric field. Summary of the Invention

[0006] Aiming at the technical problem that in the existing organic / inorganic composite technology, the phase interface formed by introducing nano two-phase into the organic conductive polymer is relatively small, and the size and dimension are difficult to control, resulting in limited improvement in the performance of the organic composite thermoelectric material, the purpose is to provide a conductive polymer and edge-oxidized graphene thermoelectric composite material, which can improve the thermoelectric performance by introducing edge-oxidized graphene to form a larger phase interface, a small-scale microstructure and dispersed nanoparticles.

[0007] One of the purposes of the present invention is to provide a conductive polymer and edge-oxidized graphene thermoelectric composite material, including 0.1-99.9 wt% of conductive polymer and 0.1-99.9 wt% of edge-oxidized graphene, based on the total weight of the organic composite thermoelectric material of the conductive polymer and edge-oxidized graphene being 100 wt%.

[0008] Preferably, the conductive polymer is polyaniline (PANI) or poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), and the molecular weight of the conductive polymer is 20000-80000.

[0009] Preferably, based on the total weight of the polyaniline and edge-oxidized graphene thermoelectric composite material being 100 wt%, the content of polyaniline is 20-80 wt%, and the content of edge-oxidized graphene is 20-80 wt%;

[0010] Based on the total weight of the poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid and edge-oxidized graphene thermoelectric composite material being 100 wt%, the content of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid is 70-99.9 wt%, and the content of edge-oxidized graphene is 0.1-30 wt%.

[0011] Preferably, the edge-oxidized graphene (EOG) is an edge-oxidized graphene nanosheet with a thickness of 0.3-20 nm.

[0012] Preferably, the edge-oxidized graphene nanosheet is prepared by the following method:

[0013] Step S1: Prepare the edge oxidized graphene mixture. Under an ice-water bath at 0 - 5°C, take graphite, sodium nitrate, and concentrated sulfuric acid and place them in a flask and stir for 10 - 15 min; then slowly add potassium permanganate at 0 - 20°C; then raise the temperature to 30 - 40°C and continue stirring for 20 - 40 min; after the first addition of water and stirring for 10 - 20 min, add water and 30 wt% H2O2 again and react for 5 - 10 min to obtain the edge oxidized graphene mixture; wherein, the dosage ratio of graphite: sodium nitrate: concentrated sulfuric acid: potassium permanganate: the first addition of water: the second addition of water: 30 wt% H2O2 is 1 g: 0.1 g - 0.3 g: 18 mL - 30 mL: 1 - 2 g: 80 - 100 mL: 200 - 300 mL: 10 - 20 mL;

[0014] Step S2: Prepare edge oxidized graphene nanosheets. Centrifuge the edge oxidized graphene mixture obtained in Step S1 in a centrifuge at 5000 - 7000 r / min for 5 - 10 min to obtain a black product; then wash the black product with 3 - 10 wt% HCl solution, ultrasonically clean it with a 53 KHz ultrasonic cleaner for 4 - 5 h, place the black product in a dialysis bag with a molecular weight cut-off of 8000 - 14000, and then place the dialysis bag containing the black product in water for dialysis for 7 - 10 days, changing the water 1 - 2 times a day; after dialysis, collect the edge oxidized graphene and dry it under vacuum at 50 - 80°C for 12 - 48 h, and then grind it to obtain the edge oxidized graphene nanosheets.

[0015] Preferably, use the powder mixing method, solution medium dispersion method, or in-situ polymerization method to prepare the conductive polymer and edge oxidized graphene thermoelectric composite material with conductive polymer monomers and edge oxidized graphene nanosheets as raw materials.

[0016] Preferably, continue to use the direct pressing method to make the prepared conductive polymer and edge oxidized graphene thermoelectric composite material into a conductive polymer and edge oxidized graphene thermoelectric composite film.

[0017] Preferably, the direct pressing method means: put the conductive polymer and edge oxidized graphene thermoelectric composite material into a tablet press and press it at 5 - 20 MPa for 0.5 - 15 min to obtain the conductive polymer and edge oxidized graphene thermoelectric composite film.

[0018] Preferably, the conductive polymer and edge oxidized graphene thermoelectric composite material prepared by the powder mixing method, solution medium dispersion method, or in-situ polymerization method is completely dissolved in an organic solvent containing an organic acid to obtain a conductive polymer and edge oxidized graphene thermoelectric composite material solution;

[0019] Then, the solution of the conductive polymer and the edge-oxidized graphene thermoelectric composite material is coated on a substrate by spraying, spin coating, doctor blading, casting or drop coating, dried, and peeled off to obtain a conductive polymer and edge-oxidized graphene thermoelectric thin film.

[0020] Preferably, the method for preparing a polyaniline and edge-oxidized graphene (PANI / EOG) thermoelectric composite thin film and polyaniline and edge-oxidized graphene (PANI / EOG) using the solution medium dispersion method includes the following steps:

[0021] Step P1: Prepare polyaniline particles. Aniline is subjected to vacuum distillation at 60-100 °C for 1-8 h to obtain high-purity aniline; 1 mL of aniline is measured with a pipette and dissolved in 40-70 mL of an inorganic acid solution with a concentration of 0.25-2 mol / L to obtain an aniline solution, and the inorganic acid is selected from one or more of the substances in the group consisting of hydrochloric acid, sulfuric acid, nitric acid, perchloric acid, and phosphoric acid; ammonium persulfate is dissolved in deionized water to obtain an ammonium persulfate solution, and the molar ratio of aniline to ammonium persulfate is 1:0.5-1:1.5, preferably 1:1.25; the ammonium persulfate solution is dropped into the aniline solution at a dropping rate of 1-5 ml / min, ice-bathed at 0-5 °C, and mechanically stirred at 100-500 rmp / min for 6-48 h for free radical polymerization to obtain a dark green product, and the product is washed 2-6 times with water, ethanol, and vacuum filtered with a vacuum pump to remove ammonium persulfate in the dark green product; the washed product is placed in a vacuum oven at 40-80 °C and vacuum dried for 6-24 h to obtain the polyaniline particles.

[0022] Step P2: Prepare polyaniline and edge-oxidized graphene (PANI / EOG) thermoelectric thin film materials; based on the total weight of the organic composite thermoelectric material of polyaniline and edge-oxidized graphene being 100 wt%, take 20 - 80 wt% of edge-oxidized graphene nanosheets (EOG) and place them in a mortar to mix with 80 - 20 wt% of polyaniline particles and mechanically grind to obtain 1 g of a uniformly mixed polyaniline and edge-oxidized graphene mixed powder. Then, add an organic acid and 2 - 10 ml of an organic solvent to the mixed powder until it is completely dissolved, and then stir on a magnetic stirrer at 60 - 100 °C for 1 - 12 h to obtain a completely dissolved polyaniline and edge-oxidized graphene solution. Among them, the mass ratio of polyaniline to the organic acid is 1:0.5 - 1:1.5, and the organic acid is selected from one or more of the substances in the group consisting of dodecylbenzenesulfonic acid, dodecylsulfonic acid, naphthalenesulfonic acid, 2,4-dinitronaphthol-7-sulfonic acid, salicylic acid, camphorsulfonic acid, acetic acid, and p-toluenesulfonic acid; the organic solvent is selected from one or more of the substances in the group consisting of m-cresol, N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, ethylene glycol, cresol, and α-terpineol; clean the substrate to remove surface stains, and the substrate is one or more of glass, silicon wafer, polyimide film, or polyethylene terephthalate film; then, coat 0.5 mL of the polyaniline and edge-oxidized graphene solution on a 2 substrate of 1×1 cm by spraying method, spin coating method, doctor blade method, casting method, or drop coating method, and then place the substrate on a hot plate at 40 - 100 °C and heat for 0.5 - 6 h to obtain a dried polyaniline and edge-oxidized graphene thin film substrate; soak the obtained polyaniline and edge-oxidized graphene thin film substrate in 3 - 10 mL of deionized water for 30 - 600 s to obtain a self-supporting polyaniline and edge-oxidized graphene thermoelectric thin film.

[0023] Preferably, the method for preparing polyaniline and edge-oxidized graphene (PANI / EOG) thermoelectric thin films and polyaniline and edge-oxidized graphene (PANI / EOG) thermoelectric composite thin film materials using the powder mixing method includes: based on the total weight of the organic composite thermoelectric material of polyaniline and edge-oxidized graphene being 100 wt%, take 20 - 80 wt% of edge-oxidized graphene nanosheets (EOG) and place them in a mortar to mix with 80 - 20 wt% of the polyaniline particles obtained in the above step S1 and mechanically grind to obtain a uniformly mixed polyaniline and edge-oxidized graphene mixed powder, put it into a tablet press, and press at 5 - 20 MPa for 0.5 - 15 min to obtain a polyaniline and edge-oxidized graphene (PANI / EOG) thermoelectric composite thin film.

[0024] Preferably, the method for preparing polyaniline and edge-oxidized graphene (PANI / EOG) thermoelectric thin films and polyaniline and edge-oxidized graphene (PANI / EOG) thermoelectric composite thin film materials using the in-situ polymerization method includes the following steps:

[0025] Step T1: Prepare polyaniline and edge-oxidized graphene (PANI / EOG) particles. Aniline is distilled under reduced pressure at 60 - 100 °C for 1 - 8 h to obtain high-purity aniline. Take 0.25 g - 4 g of edge-oxidized graphene nanosheets and place them in 10 - 70 mL of an inorganic acid solution with a concentration of 0.25 - 2 mol / L and ultrasonicate for 2 - 10 h to obtain an edge-oxidized graphene dispersion. The inorganic acid is selected from one or more of the substances in the group consisting of hydrochloric acid, sulfuric acid, nitric acid, perchloric acid, and phosphoric acid. Then, use a pipette to measure 1 mL (about 1 g) of high-purity aniline into the edge-oxidized graphene dispersion and ultrasonicate for 0.5 - 2 h to obtain a mixed solution of aniline and edge-oxidized graphene. Dissolve ammonium persulfate in 2 - 60 mL of deionized water to obtain an ammonium persulfate solution. The molar ratio of aniline to ammonium persulfate is 1:0.5 - 1:1.5, preferably 1:1.25. Drop the ammonium persulfate solution into the above-mentioned mixed solution of aniline and edge-oxidized graphene (dropwise addition rate of 1 - 5 ml / min), and under an ice bath, mechanically stir at 100 - 500 rmp / min for 6 - 48 h to carry out free radical polymerization to obtain a dark green product. The dark green product is washed with water and ethanol 2 - 6 times and filtered by a vacuum pump to remove ammonium persulfate in the dark green product. The washed product is placed in a vacuum oven at 40 - 80 °C and vacuum dried for 6 - 24 h to obtain polyaniline and edge-oxidized graphene (PANI / EOG) particles containing 20 - 80 wt% of edge-oxidized graphene.

[0026] Step T2a: Prepare polyaniline and edge-oxidized graphene (PANI / EOG) thermoelectric thin films. Add an organic acid and 2 - 10 mL of an organic solvent to the polyaniline and edge-oxidized graphene particles obtained in Step T1 until the mixture is completely dissolved, and then stir on a magnetic stirrer at 60 - 100 °C at 100 - 500 rmp / min for 1 - 12 h to obtain a completely dissolved polyaniline and edge-oxidized graphene solution. Among them, the mass ratio of polyaniline to the organic acid is 1:0.5 - 1:1.5, and the organic acid is selected from one or more of the substances in the group consisting of dodecylbenzenesulfonic acid, dodecylsulfonic acid, naphthalenesulfonic acid, 2,4-dinitronaphthol-7-sulfonic acid, salicylic acid, camphorsulfonic acid, acetic acid, and p-toluenesulfonic acid; the organic solvent is selected from one or more of the substances in the group consisting of m-cresol, N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, ethylene glycol, cresol, and α-terpineol. Clean the substrate to remove surface stains and increase the contact angle. The substrate is one or more of glass, silicon wafer, polyimide film, or polyethylene terephthalate film. Then, coat 0.5 - 1 mL of the polyaniline and edge-oxidized graphene solution on a 1×1 cm 2On the substrate, the substrate is then placed on a heating plate at 40 - 100 °C and heated for 0.5 - 6 h to obtain a substrate with dried polyaniline and edge oxidized graphene film. The obtained polyaniline and edge oxidized graphene film substrate is immersed in 3 - 10 mL of deionized water for 30 - 600 s to obtain a self - supporting polyaniline and edge oxidized graphene thermoelectric film with a thickness of 10 - 500 μm.

[0027] Step T2b: Prepare a polyaniline and edge oxidized graphene (PANI / EOG) thermoelectric composite film. The polyaniline and edge oxidized graphene (PANI / EOG) particles obtained in step T1 are ground and crushed with a mortar and pestle, and then the powder is put into a tablet press and pressed at 5 - 20 MPa for 0.5 - 15 min to obtain a polyaniline and edge oxidized graphene (PANI / EOG) thermoelectric composite film material.

[0028] Preferably, a method for preparing a poly(3,4 - ethylenedioxythiophene) - polystyrene sulfonic acid and edge oxidized graphene (PEDOT:PSS / EOG) thermoelectric film using in - situ polymerization method includes the following steps:

[0029] Step W1: Prepare a mixed solution. Add edge oxidized graphene nanosheets (EOG) to an aqueous solution of polystyrene sulfonic acid (PSS) at 0.33 g / mL, stir at 100 - 500 rmp / min for 20 - 90 min, and then put it into an ultrasonic cleaner and ultrasonicate in a water bath at 5 - 15 °C for 10 - 60 min to obtain a polystyrene sulfonic acid and edge oxidized graphene (PSS / EOG) dispersion. To prevent the polystyrene sulfonic acid and edge oxidized graphene (PSS / EOG) dispersion from being oxidized, a protective gas is introduced into the polystyrene sulfonic acid and edge oxidized graphene (PSS / EOG) dispersion at a gas - filling rate of 1 - 5 L / min. The protective gas is selected from one or more of argon, nitrogen, helium, and carbon dioxide, and the gas - filling time is 30 - 90 min. Then add 3,4 - ethylenedioxythiophene (EDOT) monomer to the PSS / EOG dispersion and mechanically stir at 100 - 500 rmp / min for 20 - 80 min to obtain a mixed solution. Among them, the mass ratio of EOG:polystyrene sulfonic acid:EDOT is 3.45 mg:1 - 5 g:1 g, preferably 3.45 mg:2 - 3 g:1 g.

[0030] Step W2: Prepare a poly(3,4 - ethylenedioxythiophene) - polystyrene sulfonic acid and edge oxidized graphene (PEDOT:PSS / EOG) thermoelectric film. Add Fe 3+ (EDOT:Fe 3+The molar ratio = 1:0.001 to 1:0.1) and sodium persulfate (molar ratio of EDOT:sodium persulfate = 1:0.5 to 1:2) are added to the mixed solution obtained in step W1. A protective gas is introduced into the mixed solution at an inflation rate of 1 to 5 L / min. The protective gas is selected from one or more of argon, nitrogen, helium, and carbon dioxide. The reaction is carried out at 5 to 15 °C for 6 to 24 h, and the protective gas is introduced throughout the entire reaction process. Then, 500 to 800 ml of 732 cation exchange resin (Sinopharm, sodium form) and 717 anion exchange resin (Sinopharm, chloride form) are respectively exchanged with the PEDOT:PSS / EOG composite material mixture for 0.5 to 3 h. Then, it is filtered through a 20 to 50 μm screen filter to obtain the PEDOT:PSS / EOG composite material. Then, the substrate is cleaned to remove surface stains and increase the contact angle. The substrate is one or more of glass, silicon wafer, polyimide film, or polyethylene terephthalate film. Then, the PEDOT:PSS / EOG mixed solution is taken and coated on a 1×1 cm 2 substrate, and dried to obtain a poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid and edge oxidized graphene (PEDOT:PSS / EOG) thermoelectric film with a film thickness of 10 to 500 μm.

[0031] Preferably, the method for preparing poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid and edge oxidized graphene (PEDOT:PSS / EOG) using the solution medium dispersion method includes: placing 0.001 to 0.01 g of edge oxidized graphene nanosheets (EOG) and 0.00233 g to 9.99 g of PEDOT:PSS conductive particles (purchased from Agfa Materials Company - 1 g) in 10 ml of ethanol and ultrasonically dispersing for 0.5 to 3 h. The substrate is cleaned to remove surface stains and increase the contact angle. The substrate is one or more of glass, silicon wafer, polyimide film, or polyethylene terephthalate film. Then, the PEDOT:PSS / EOG mixed solution is taken and coated on a 1×1 cm 2 substrate, and dried to obtain a poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid and edge oxidized graphene (PEDOT:PSS / EOG) thermoelectric film containing 0.01 to 30 wt% of edge oxidized graphene with a thickness of 10 to 500 μm.

[0032] The positive and progressive effects of the present invention are as follows:

[0033] The conductive polymer and edge-oxidized graphene thermoelectric composite material provided by the present invention selects edge-oxidized graphene and organic conductive polymer for composite preparation of thermoelectric materials. Compared with the existing organic composite thermoelectric materials, the conductive polymer and edge-oxidized graphene thermoelectric composite material of the present invention forms a composite material with a large phase interface, a small-scale microstructure, and dispersed nanoparticles by introducing nano two-phase in the organic conductive polymer, that is, edge-oxidized graphene which has the advantages of being hydrophilic, easy to disperse, capable of bonding with organic substances, and at the same time maintaining good electrical properties. At the same time, by utilizing the inherently low thermal conductivity of the organic polymer, the electrical conductivity of the thermoelectric material is improved on the basis of the existing preparation technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] With reference to the accompanying drawings, the disclosure of the present invention will become more apparent. It should be understood that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In the figures:

[0035] Figure 1 is a comparison diagram of the Raman spectra of the intrinsic EOG prepared by the present invention and GO in the prior art;

[0036] Figure 2 is a comparison diagram of the infrared spectra of the intrinsic EOG prepared by the present invention and the PANI / EOG composite films prepared by the solution medium dispersion method, powder composite method, and in-situ polymerization method;

[0037] Figure 3 is a comparison diagram of the conductivity test results of the intrinsic EOG, PANI prepared by the present invention, and GO in the prior art;

[0038] Figure 4 is a comparison diagram of the conductivity (σ) test results of the PANI / EOG prepared by the present invention and the PANI / EOG composite thermoelectric film in the prior art;

[0039] Figure 5 is a comparison diagram of the conductivity (σ) test results of the PEDOT:PSS / EOG prepared by the present invention and the PEDOT:PSS / EOG composite thermoelectric film in the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0040] The following specific examples illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0041] Example 1 Preparation of Edge-Oxidized Graphene Nanosheets (EOG)

[0042] Step S1: Prepare the edge-oxidized graphene mixture. Under an ice-water bath at 0 °C, 1 g of graphite, 0.1 g of sodium nitrate, and 23 ml of concentrated hydrochloric acid are respectively placed in a flask and stirred for 10 - 15 min. 2 g of KMnO4 is slowly added thereto while controlling the system temperature to be less than 20 °C. Then the temperature is raised to 35 °C and stirred for 30 min. 90 ml of water is added and stirred for 20 min. Then, 200 ml of water and 15 ml of 30 wt% H2O2 are added and reacted for 10 min to end the reaction and obtain the edge-oxidized graphene mixture.

[0043] Step S2: Prepare edge-oxidized graphene nanosheets. The edge-oxidized graphene mixture prepared in Step S1 is centrifuged in a centrifuge at 6000 rmp for 6 minutes to obtain a black product. Then the product is washed with 5 wt% HCl and placed in a dialysis bag, dialyzed in water for 8 days (changing water twice a day). After pouring out the supernatant, the edge-oxidized graphene is collected with a watch glass and placed in a vacuum drying oven at 60 °C for drying for 12 h, and then ground to obtain edge-oxidized graphene nanosheets with a thickness of 5 nm.

[0044] Example 2 uses the solution medium dispersion method to prepare a polyaniline and edge-oxidized graphene (PANI / EOG) thermoelectric composite film material

[0045] Step P1: Prepare polyaniline particles. Aniline is distilled under reduced pressure at 80 °C for 6 h to obtain high-purity aniline. 1 mL of aniline measured with a pipette is dissolved in 50 mL of hydrochloric acid with a concentration of 0.1 mol / L to obtain an aniline solution. 2.5 g of ammonium persulfate is dissolved in 50 mL of deionized water to obtain an ammonium persulfate solution. The ammonium persulfate solution is dropped into the above aniline solution at a dropping rate of 1 ml / min, and ice-bathed at 5 °C and mechanically stirred at 200 rmp / min for 12 h for free radical polymerization to obtain a dark green product. The product is washed with water and ethanol three times and vacuum filtered with a vacuum pump to remove ammonium persulfate in the dark green product. The washed product is placed in a vacuum oven at 60 °C for vacuum drying for 12 h to obtain polyaniline particles with a molecular weight of 80,000 - 100,000.

[0046] Step P2: Prepare a polyaniline and edge-oxidized graphene (PANI / EOG) thermoelectric composite film. The polyaniline particles obtained in S1 are ground with a mortar and pestle to obtain polyaniline powder. 0.02 g of edge-oxidized graphene nanosheets (EOG) is placed in a mortar and mixed with 0.08 g of polyaniline powder and mechanically ground to obtain a uniformly mixed polyaniline and edge-oxidized graphene mixed powder. 0.1 g of camphorsulfonic acid and 5 mL of m-cresol solvent are added to the composite powder, and then stirred at 300 rmp / min on a magnetic stirrer at 90 °C for 4 h to obtain a completely dissolved polyaniline and edge-oxidized graphene solution. Then, the polyaniline and edge-oxidized graphene solution is drop-coated on a 1×1 cm 2On the cleaned glass substrate, the substrate was then placed on a heating plate at 80 °C and heated for 5 h to obtain a dried polyaniline and edge oxidized graphene thin film substrate. The obtained polyaniline and edge oxidized graphene thin film substrate was immersed in 10 mL of deionized water for 300 s to obtain a self-supporting polyaniline and edge oxidized graphene thermoelectric thin film with a thickness of 20 μm and containing 20 wt% edge oxidized graphene.

[0047] Example 3 used the powder composite method to prepare polyaniline and edge oxidized graphene (PANI / EOG) thermoelectric composite thin film materials

[0048] The polyaniline particles obtained in step S1 of Example 2 were ground with a mortar and pestle to obtain polyaniline powder. 20 wt% edge oxidized graphene nanosheets (EOG) were taken and placed in a mortar and mixed with 80 wt% polyaniline powder and mechanically ground to obtain a uniformly mixed polyaniline and edge oxidized graphene mixed powder. The polyaniline and edge oxidized graphene mixed powder was put into a tablet press and pressed at 10 MPa for 1 min to obtain a conductive polymer and edge oxidized graphene thermoelectric composite thin film material with a thickness of 440 μm and containing 20 wt% edge oxidized graphene.

[0049] Example 4 used the in-situ polymerization method to prepare polyaniline and edge oxidized graphene (PANI / EOG) thin films and polyaniline and edge oxidized graphene (PANI / EOG) thermoelectric composite thin film materials

[0050] Step T1: Prepare polyaniline and edge oxidized graphene (PANI / EOG) particles. Aniline was distilled under reduced pressure at 80 °C for 6 h to obtain high-purity aniline. 0.25 g of edge oxidized graphene nanosheets were placed in 50 mL of 0.1 mol / L hydrochloric acid solution and ultrasonicated in a 53 KHz ultrasonic cleaner for 5 h to obtain an edge oxidized graphene dispersion. Then, 1 ml of high-purity aniline was measured with a pipette and added to the edge oxidized graphene dispersion and ultrasonically dispersed for another 1 h to obtain an aniline and edge oxidized graphene mixed solution. 2.5 g of ammonium persulfate was dissolved in 50 mL of deionized water to obtain an ammonium persulfate solution. The ammonium persulfate solution was dropped into the aniline and edge oxidized graphene mixed solution at a dropping rate of 1 ml / min, and ice-bathed and mechanically stirred at 0 °C for 12 h for free radical polymerization to obtain a dark green product. The product was washed 3 times with water and vacuum filtered with a vacuum pump to remove ammonium persulfate in the dark green product. The washed product was placed in a vacuum drying oven at 60 °C and vacuum dried for 12 h to obtain 80,000 - 100,000 polyaniline and edge oxidized graphene (PANI / EOG) particles containing 20 wt% edge oxidized graphene.

[0051] Step T2: Prepare a polyaniline and edge-oxidized graphene (PANI / EOG) thermoelectric thin film. Add 0.064 g of camphorsulfonic acid and 5 mL of m-cresol to 0.05 g of the polyaniline and edge-oxidized graphene particles obtained in Step T1, and then stir at 300 rmp / min on a magnetic stirrer at 90 °C for 4 h to obtain a completely dissolved polyaniline and edge-oxidized graphene solution. Then, drop-coat the polyaniline and edge-oxidized graphene solution onto a cleaned glass substrate of 1×1 cm 2 , and then place the substrate on a hot plate at 80 °C and heat for 5 h to obtain a dried polyaniline and edge-oxidized graphene thin film substrate. Immerse the obtained polyaniline and edge-oxidized graphene thin film substrate in 10 mL of deionized water for 300 s to obtain a self-supporting polyaniline and edge-oxidized graphene thermoelectric thin film with a thickness of 20 μm and containing 20 wt% of edge-oxidized graphene.

[0052] Example 5: Prepare a poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid and edge-oxidized graphene (PEDOT:PSS / EOG) thermoelectric thin film using an in-situ polymerization method

[0053] Step W1: Prepare a mixed solution. Add 3.45 mg of edge-oxidized graphene nanosheets (EOG) to 0.66 ml of an aqueous solution of polystyrene sulfonic acid (PSS, molecular weight 75000) with a concentration of 0.33 g / ml (i.e., containing 2 g of PSS), stir at 200 rmp / min for 30 min, and then place it in a 53 KHz ultrasonic cleaner and ultrasonicate in a water bath at 10 °C for 30 min to obtain a polystyrene sulfonic acid and edge-oxidized graphene (PSS / EOG) dispersion. To prevent the polystyrene sulfonic acid and edge-oxidized graphene (PSS / EOG) dispersion from being oxidized, nitrogen is filled into the polystyrene sulfonic acid and edge-oxidized graphene (PSS / EOG) dispersion at a filling rate of 3 L / min for 60 min. Then, add 1 ml of 3,4-ethylenedioxythiophene (EDOT) monomer to the PSS / EOG dispersion and mechanically stir at 200 rmp / min for (30) min to obtain a mixed solution.

[0054] Step W2: Prepare a poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid and edge-oxidized graphene (PEDOT:PSS / EOG) thermoelectric thin film. Add 0.001 mol of Fe 3+And 0.75 mol of sodium persulfate was added to the mixed solution obtained in step W1, and a protective gas was introduced into the mixed solution at an inflation rate of 4 L / min. The protective gas was selected from one or more of argon, nitrogen, helium, and carbon dioxide, and the reaction was carried out for 24 h at 12 °C. The protective gas was introduced throughout the entire reaction process. Then, 400 ml of a mixed ion exchange resin of 732 cation exchange resin (Sinopharm, sodium form) and 717 anion exchange resin (Sinopharm, chloride form) was exchanged with the PEDOT:PSS / EOG composite material mixture for 3 h. Then, it was filtered through a 20 - 50 μm sieve filter to obtain the PEDOT:PSS / EOG composite material. Then, the obtained PEDOT:PSS / EOG mixed solution was spin-coated on a cleaned glass substrate of 1×1 cm 2 to obtain a poly(3,4-ethylenedioxythiophene) (molecular weight ~80000)-polystyrenesulfonic acid and edge oxidized graphene (PEDOT:PSS / EOG) thermoelectric thin film with a thickness of 5 μm containing 0.1 wt% of edge oxidized graphene after drying.

[0055] Example 6 used the solution medium dispersion method to prepare a poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid and edge oxidized graphene (PEDOT:PSS / EOG) thermoelectric thin film.

[0056] 1 mg of edge oxidized graphene nanosheets (EOG) and 0.999 g of PEDOT:PSS conductive particles (purchased from Agfa Materials Company - 1 g) were placed in 10 ml of ethanol and ultrasonically dispersed for 2 h. The glass substrate was cleaned to remove surface stains and increase the contact angle. Then, the obtained PEDOT:PSS / EOG mixed solution was spin-coated on a substrate of 1×1 cm 2 to obtain a poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid and edge oxidized graphene (PEDOT:PSS / EOG) thermoelectric thin film with a thickness of 5 μm containing 0.1 wt% of edge oxidized graphene after drying.

[0057] Performance test examples

[0058] As Figure 1 shown, Figure 1 this is a comparison chart of the Raman spectra of the intrinsic state EOG prepared by the present invention and GO in the prior art.

[0059] As can be seen from the figure, characteristic peaks of carbon materials, the D peak and the G peak, appeared near 1350 cm and 1580 cm for EOG. Among them, the appearance of the D peak indicates the presence of a disordered structure caused by defects in the carbon material structure. The stronger the intensity of the D peak, the more defects exist in the structure of the material, and the higher the degree of disorder of the material; the G peak is used to characterize the SP 2 ordered structure of carbon atoms. After calculation, the I D / IG was 1.71, while that of edge oxidized graphene (EOG) was D / G = 1.02, indicating that the defects on the EOG surface are less than those of GO, which is more conducive to the flow of carriers, thereby improving the thermoelectric performance of the material. It should be noted that the above-mentioned GO was prepared by the Hummer method, and the above-mentioned EOG is the edge oxidized graphene nanosheet prepared in Example 1 of the present invention.

[0060] As Figure 2 shown, Figure 2 is the infrared spectrum comparison chart of the intrinsic EOG prepared in the present invention and the PANI / EOG composite films prepared by the solution medium dispersion method, powder composite method and in-situ polymerization method.

[0061] Among them, EOG is the edge oxidized graphene nanosheet prepared in Example 1 of the present invention; the method for preparing the PANI / EOG film by the solution medium dispersion method is specifically as shown in Example 2; the method for preparing the PANI / EOG film by the powder composite method is specifically as shown in Example 3; the method for preparing the PANI / EOG film by the in-situ polymerization method is specifically as shown in Example 4. It should be noted that the preparation method of the PANI / GO film is the same as that of the PANI / EOG film, only replacing the edge oxidized graphene (EOG) with graphene oxide (GO).

[0062] According to Figure 2 the test results in the infrared spectrum comparison chart, the differences between PANI / EOG and EOG can be clearly observed. The peak intensity near 1055 cm -1 is a measure of the degree of electron delocalization, and that of the PANI / EOG composite material increases and shifts slightly, indicating that there is an interaction between the π bond of EOO and the conjugated structure of PANI.

[0063] As Figure 3 shown, Figure 3 is the comparison chart of the conductivity test results of the intrinsic EOG, PANI prepared in the present invention and GO in the prior art, which was measured by a CH-320 Hall test system. Among them, graphene oxide (GO) was prepared by the Hummer method, edge oxidized graphene (EOG) is the edge oxidized graphene nanosheet prepared in Example 1 of the present invention, and PANI is the polyaniline prepared in step P1 of Example 2.

[0064] Through Figure 3 , it can be clearly seen that the conductivity of the intrinsic EOG is significantly higher than that of GO. This is mainly because only a small amount of oxygen-containing functional groups are modified on the edge of graphene in the present invention, with few internal defects, and the conjugated structure of graphene is retained to the greatest extent, so the conductivity of edge oxidized graphene is better than that of graphene oxide.

[0065] As Figure 4 shown Figure 4 Figure 4 This is a comparison chart of the conductivity (σ) test results of PANI / EOG prepared by the present invention and PANI / EOG composite thermoelectric thin films in the prior art. This test was measured by a CH-320 Hall test system.

[0066] From Figure 4 Figure 4 the comparison of the conductivity test results in [reference], it can be seen that the conductivities of the composites of the conductive polymer polyaniline (PANI) and edge oxidized graphene (EOG) prepared by the solution medium dispersion method (Example 2), the powder composite method (Example 3), and the in-situ polymerization method (Example 4) are all higher than those of the composite thin films of polyaniline and graphene oxide prepared by the prior art. At the same time, from the test results of Figure 4 Figure 4 it can also be known that: the conductivity of the composite material prepared by the in-situ polymerization method in the present invention is greater than that of the composite material prepared by the solution medium dispersion method, which is greater than that of the composite material prepared by the powder mixing method, that is, σ 原位聚合法 >σ 溶液介质分散法 >σ 粉体混合法 粉体混合法 , and from the infrared characterization diagram, the reason is that the in-situ polymerization method is a chemical method, and there is a π-π interaction between the organic matter and EOG, rather than just a simple physical mixture; while in the solution medium dispersion method, organic acids and m-cresol solvents are added, making the PANI molecular chain more ordered, and at the same time, there is a small amount of bonding between polyaniline and edge oxidized graphene, thus resulting in σ 原位聚合法 >σ 溶液介质分散法 >σ 粉体混合法 .

[0067] As Figure 5 shown Figure 5 Figure 5 This is a comparison chart of the conductivity (σ) test results of PEDOT:PSS / EOG prepared by the present invention and PEDOT:PSS / EOG composite thermoelectric thin films in the prior art. This test was measured by a CH-320 Hall test system.

[0068] Through Figure 5 Figure 5 the conductivity test results in [reference], it can be seen that the conductivities of the composites of the conductive polymer poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT:PSS) and edge oxidized graphene (EOG) prepared by the in-situ polymerization method (Example 5) and the solution medium dispersion method (Example 6) are significantly higher than those of the composite thin films of poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT:PSS) and graphene oxide prepared by the prior art. At the same time, the conductivity of the composite material prepared by the in-situ polymerization method is greater than that of the composite material prepared by the solution medium dispersion method, that is, σ 原位聚合法 >σ 溶液介质分散法, it can be seen from the infrared characterization diagram that the reason is that the in-situ polymerization method is a chemical method, and there is a π-π interaction between the organic matter and EOG, while the composite material prepared by the solution medium dispersion method is only slightly bonded, thus resulting in σ 原位聚合法 >σ 溶液介质分散法 .

[0069] The present invention has been described in detail above in conjunction with the accompanying drawings and embodiments. Those of ordinary skill in the art can make various variations of the present invention according to the above description. Therefore, certain details in the embodiments should not constitute a limitation to the present invention, and the scope of the present invention will be defined by the scope of the appended claims.

Claims

1. A conductive polymer and edge-oxidized graphene thermoelectric composite material, characterized in that, The conductive polymer and edge-oxidized graphene thermoelectric composite material comprises 0.1-99.9 wt% of a conductive polymer and 0.1-99.9 wt% of edge-oxidized graphene, based on the total weight of the conductive polymer and edge-oxidized graphene organic composite thermoelectric material being 100 wt%. Among them, the edge-oxidized graphene is edge-oxidized graphene nanosheets with a thickness of 0.3-20 nm, and the edge-oxidized graphene nanosheets are prepared by the following method: Step S1: Prepare an edge-oxidized graphene mixed solution. Under an ice-water bath at 0-5 °C, respectively take graphite, sodium nitrate, and concentrated sulfuric acid and place them in a flask and stir for 10-15 min; then slowly add potassium permanganate at 0-20 °C; then raise the temperature to 30-40 °C and continue to stir for 20-40 min; after the first addition of water and stirring for 10-20 min, add water and 30 wt% H2O2 again and react for 5-10 min to obtain the edge-oxidized graphene mixed solution; among them, the dosage ratio of graphite:sodium nitrate:concentrated sulfuric acid:potassium permanganate:first addition of water:second addition of water:30 wt% H2O2 is 1 g:0.1 g-0.3 g:18 mL-30 mL:1-2 g:80-100 mL:200-300 mL:10-20 mL; Step S2: Prepare edge-oxidized graphene nanosheets. Centrifuge the edge-oxidized graphene mixed solution obtained in Step S1 in a centrifuge at 5000-7000 r / min for 5-10 min to obtain a black product; then wash the black product with a 3-10 wt% HCl solution, ultrasonically clean it with a 53 KHz ultrasonic cleaner for 4-5 h, place the black product in a dialysis bag with a molecular weight cut-off of 8000-14000, and then place the dialysis bag containing the black product in water for dialysis for 7-10 days, changing the water 1-2 times a day; after dialysis, collect the edge-oxidized graphene and dry it under vacuum conditions at 50-80 °C for 12-48 h, and then grind it to obtain the edge-oxidized graphene nanosheets.

2. The conductive polymer and edge-oxidized graphene thermoelectric composite material according to claim 1, wherein The conductive polymer is polyaniline or poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid, and the molecular weight of the conductive polymer is 80000-100000.

3. The conductive polymer and edge-oxidized graphene thermoelectric composite material according to claim 2, wherein Based on the total weight of the polyaniline and edge-oxidized graphene thermoelectric composite material being 100 wt%, the polyaniline content is 20-80 wt%, and the edge-oxidized graphene content is 20-80 wt%; Based on the total weight of the poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid and edge-oxidized graphene thermoelectric composite material being 100 wt%, the poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid content is 70-99.9 wt%, and the edge-oxidized graphene content is 0.1-30 wt%.

4. The conductive polymer and edge-oxidized graphene thermoelectric composite material according to claim 1, wherein The conductive polymer and edge-oxidized graphene thermoelectric composite material is prepared from a conductive polymer monomer and edge-oxidized graphene nanosheets by using a powder mixing method, a solution medium dispersion method, or an in-situ polymerization method.

5. The conductive polymer and edge-oxidized graphene thermoelectric composite material according to claim 4, wherein The obtained conductive polymer and edge-oxidized graphene thermoelectric composite material are further made into a conductive polymer and edge-oxidized graphene thermoelectric composite film material by using the direct pressing method.

6. The conductive polymer and edge-oxidized graphene thermoelectric composite material according to claim 5, wherein The direct pressing method refers to: putting the conductive polymer and edge-oxidized graphene thermoelectric composite material into a tablet press and pressing at 5-20 MPa for 0.5-15 minutes to obtain the conductive polymer and edge-oxidized graphene thermoelectric composite film material.

7. The conductive polymer and edge-oxidized graphene thermoelectric composite material according to claim 4, wherein The conductive polymer and edge-oxidized graphene thermoelectric composite material prepared by using the powder mixing method, solution medium dispersion method or in-situ polymerization method are completely dissolved in an organic solvent containing an organic acid to obtain a conductive polymer and edge-oxidized graphene thermoelectric composite material solution; Then, the conductive polymer and edge-oxidized graphene thermoelectric composite material solution is coated on a substrate by spraying, spin coating, blade coating, casting or drop coating, dried, and peeled off to obtain a conductive polymer and edge-oxidized graphene thermoelectric film.

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