WO2018187921A1

WO2018187921A1 - Improved preparation method for graphene oxide

Info

Publication number: WO2018187921A1
Application number: PCT/CN2017/079980
Authority: WO
Inventors: 钟玲珑
Original assignee: 深圳市佩成科技有限责任公司
Priority date: 2017-04-11
Filing date: 2017-04-11
Publication date: 2018-10-18

Abstract

Provided is an improved preparation method for graphene oxide. The method comprises pre-oxidation, washing and drying, oxidization, termination reaction, removal of potassium permanganate, washing and concentration, and ultrasonic dialysis, thereby obtaining a graphene oxide solution. The graphene oxide prepared using the method combines the advantages of relatively high electrical conductivity and a relatively large specific surface area of graphene as well as good mechanical properties of cellulose such as CEC and CEHEC.

Description

Improved method for preparing graphene oxide

Technical field

[0001] The present invention relates to an improved method for preparing graphene oxide, which belongs to the field of preparation of high dielectric materials.

Background technique

[0002] High dielectric materials are a widely used insulating material, and because of its excellent electrical storage and uniform electric field properties, it has very important applications in the electronics, motor and cable industries. With the development of high performance and size miniaturization of many important electronic devices such as capacitors, resonators, filters, and memories, high dielectric materials are receiving more and more attention. At present, high dielectric materials are widely used. Traditional ceramic materials have high brittleness, high processing temperature and high loss; polymer materials have excellent processing properties, but usually have a low dielectric constant.

technical problem

[0003] At present, most of the high dielectric materials have their own limitations, the polymer is light, easy to process, has multi-scale structure and special flexibility, so that polymer-based composite materials are widely studied as a new type of high dielectric materials. . In order to improve the comprehensive dielectric properties of polymer-based composites, including maximizing the dielectric constant of materials, reducing dielectric loss, and ensuring the dielectric strength of materials, we use a combination of polymers and graphene. Graphene is a novel two-dimensional atomic crystal composed of a single atomic layer of carbon atoms connected by sp ² hybridization. It has become a hot spot in nanomaterials research with its excellent mechanical, electrical and optical properties.

Problem solution

Technical solution

In view of the above deficiencies of the prior art, it is an object of the present invention to provide an improved method for preparing graphene oxide.

[0005] The object of the present invention is to provide an improved method for preparing graphene oxide in order to overcome the deficiencies of materials prepared by conventional preparation methods. In order to achieve the above object, the present invention adopts the following technical solutions: [0006] The present invention provides an improved method for preparing graphene oxide, comprising the following steps:

[0007] Step 1. Pre-oxidation, heating concentrated sulfuric acid, adding potassium persulfate and phosphorus pentoxide, controlling the temperature and stirring until the reactants are all dissolved. After the temperature of the reaction system is lowered, graphite powder is added, and the reactant is added. The mixture was heated with stirring under a water bath, then cooled to room temperature, and the resulting product was stirred at room temperature overnight after dilution;

[0008] Step two, washing and drying, suction filtration of the product, and washing, until the solution obtained by the last suction filtration is neutral, and then evaporate the solid on the core funnel into a semi-dry state;

[0009] Step three, oxidation, the concentrated sulfuric acid is poured into, and cooled with an ice water bath, and then the above product and potassium permanganate are slowly added without stirring, maintaining the temperature of the reaction system until the reactants are completely dissolved; 0010] Step 4, terminate the reaction, add deionized water to the reaction system, control the temperature of the reaction system, remove the reactants, add deionized water and stir the reaction;

[0011] Step 5, remove potassium permanganate, add hydrogen peroxide to the reaction system, continue to stir and then stand overnight; [0012] Step 6, wash and concentrate, remove the supernatant, rinse with HC1 solution, and then reuse Rinse with deionized water until the solution is neutral, and then centrifuge the product to obtain a high concentration of graphite oxide.

[0013] Step 7. Ultrasonic dialysis, the obtained graphite oxide is diluted with water, then subjected to ultrasonic treatment, and dialyzed for one to two weeks to obtain a yellow-brown uniformly dispersed single-layer graphite oxide dilute solution.

[0014] Preferably, the concentrated sulfuric acid in the above step 1 is 25 mL, and the potassium persulfate and the phosphorus pentoxide are each 5

[0015] Preferably, in the above step 1, the temperature of the reaction system is lowered to 80 ° C, and 6 g of graphite powder is added to form a foam, and the foam gradually subsides within 30 min.

[0016] Preferably, in the above step 1, the reactant is heated under stirring in a water bath at 80 ° C for 4.5 h, then cooled to room temperature, diluted with 1 L of deionized water, and the obtained product is stirred at room temperature overnight.

[0017] Preferably, after the above step three, the water bath is heated to 35. C, the reaction system continues to react at this temperature for 2 h

[0018] Preferably, in the above step four, as the water is continuously added, the activity of the reactants is continuously lowered until the finally added deionized water no longer causes a significant temperature change.

[0019] Preferably, in the process of adding hydrogen peroxide in the above step 5, the system first changes from dark brown to brown, then to earthy yellow, and finally to orange yellow.

[0020] Preferably, the hydrogen peroxide in the above step 5 is 25 mL and 30%, and the stirring is continued for 30 minutes.

[0021] Preferably, the HCl solution in the above step 6 is 5%. Advantageous effects of the invention

Beneficial effect

[0022] The improved method for preparing graphene oxide provided by the invention, the prepared graphene oxide comprehensively has the advantages of high conductivity, large specific surface area and good mechanical properties of CEC and CEHEC. Brief description of the diagram

DRAWINGS

1 is a schematic diagram of a UV-vis spectrum of graphene oxide prepared by the present invention.

Embodiments of the invention

[0024] The present invention provides an improved method for preparing graphene oxide. The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention

[0025] The improved method for preparing graphene oxide provided by the embodiment specifically includes the following steps:

[0026] 1) Pre-oxidation: Add 25 mL of concentrated sulfuric acid to a 100 mL Erlenmeyer flask, heat the temperature to 90 ° C, then add 5 g of potassium persulfate and 5 g of phosphorus pentoxide to control the temperature at 80-100 Stir at °C for 20 min until the reaction was completely dissolved. Then, the temperature of the reaction system was lowered to 80 ° C, 6 g of graphite powder was added, foam appeared, and the foam gradually subsided within 30 min. The reaction was heated in a water bath at 80 ° C for 4.5 h, and then cooled to It was diluted with 1 L of deionized water at room temperature and the obtained product was stirred at room temperature overnight.

2) Washing and drying: The obtained product was suction filtered, and washed with a large amount of deionized water until the solution obtained by the last suction filtration was neutral, and then the solid on the core funnel was evaporated to a semi-dry state.

[0028] 3) Oxidation: Pour 230 mL of concentrated sulfuric acid into a 1 L Erlenmeyer flask and cool to 0 ° C with an ice water bath, then slowly add the above product (pre-oxidized graphite) and 30 g of potassium permanganate in sequence. Add to the Erlenmeyer flask, stirring constantly, and keep the temperature of the reaction system not higher than 10 ° C until the reactants are completely dissolved. The water bath was warmed to 35 ° C, and the reaction system was allowed to continue to react at this temperature for 2 h.

[0029] 4) Stop the reaction: Add 460 mL of deionized water to the reaction system (initially deionized water should be slowly added) In), the temperature of the reaction system is controlled to be lower than 50 °C. As water continues to be added, the activity of the reactants continues to decrease until the last added deionized water no longer causes significant temperature changes. The reaction was transferred to a 2 L beaker, then 1.4 L of deionized water was added and the reaction was stirred for 2 h.

[0030] 5) Removal of potassium permanganate: 25 mL of 30% hydrogen peroxide was added to the reaction system. In the process, the system first changed from dark brown to brown, then to earthy yellow, and finally to orange-yellow. Stirring was continued for 30 min and allowed to stand overnight.

6) Washing and concentrating: The supernatant was removed, rinsed with a large amount of 5% HCl solution, and then rinsed with a large amount of deionized water until the resulting solution was neutral. Finally, the obtained product was centrifuged to obtain a high concentration of graphite oxide.

7) Ultrasonic dialysis: The obtained graphite oxide was diluted with water, then ultrasonicated, and dialyzed for one to two weeks to obtain a yellow-brown uniformly dispersed single-layer graphite oxide dilute solution.

[0033] As can be seen from FIG. 1, the graphene oxide has two absorption peaks in the test range, which are located near 230 nm and 300 nm, respectively. The absorption peak at 230 nm is due to the π electron absorption of the aromatic C=C bond, which shifts to the π* anti-bond orbital, while the weaker shoulder at 300 nm is due to the C=0 bond. The n electrons on the bond orbit absorb the energy and then transition to the π* anti-bond orbit.

The method for preparing the improved graphene oxide provided by the invention has the advantages that the graphene oxide has a high electrical conductivity, a large specific surface area, and good mechanical properties of CEC and CEHEC.

[0035]

[0036] It is to be understood that those skilled in the art can make equivalent substitutions or changes in accordance with the technical solutions of the present invention and the inventive concepts thereof, and all such changes or substitutions should belong to the appended claims. protected range.

Claims

Claim

[Claim 1] An improved method for preparing graphene oxide, characterized in that: the preparation method comprises the following steps:

Step one, pre-oxidation, heating concentrated sulfuric acid, adding potassium persulfate and phosphorus pentoxide, controlling the temperature and stirring until the reactants are all dissolved;

After the temperature of the reaction system is lowered, graphite powder is added, and the reactant is heated under stirring in a water bath, and then cooled to room temperature. After dilution, the obtained product is stirred at room temperature overnight; Step 2, washing and drying, and suction-filtering the obtained product, And washing, until the solution obtained by the last suction filtration is neutral, and then evaporating the solid on the core funnel into a semi-dry state; Step 3, oxidizing, pouring concentrated sulfuric acid, and cooling with an ice water bath, and then sequentially The product and potassium permanganate are slowly added without stirring, maintaining the temperature of the reaction system until the reactants are completely dissolved;

Step 4, the reaction is terminated, deionized water is added to the reaction system, the temperature of the reaction system is controlled, the reactant is removed, and deionized water is added and stirred;

Step 5, removing potassium permanganate, adding hydrogen peroxide to the reaction system, continuing to stir and then standing overnight;

Step 6. Wash and concentrate, remove the supernatant, rinse with HC1 solution, and then rinse with deionized water until the solution is neutral, and then centrifuge the obtained product to obtain high concentration of graphite oxide;

Step 7. Ultrasonic dialysis, the obtained graphite oxide is diluted with water, then subjected to ultrasonic treatment, and dialyzed for one to two weeks to obtain a yellow-brown uniformly dispersed single-layer graphite oxide dilute solution.

[Claim 2] The method for preparing improved graphene oxide according to claim 1, wherein: in the first step, the concentrated sulfuric acid is 25 mL, and the potassium persulfate and the phosphorus pentoxide are each 5 g

[Claim 3] The method for preparing improved graphene oxide according to claim 1 or 2, wherein: in the first step, the temperature of the reaction system is lowered to 80 ° C, and then 6 g of graphite powder is added. Foam appeared and the foam gradually subsided within 30 minutes.

[Claim 4] The method for preparing improved graphene oxide according to claim 1 or 2, wherein: in the step 1, the reactant is heated and heated in a water bath at 80 ° C for 4.5 h, and then cooled. To room temperature, it was diluted with 1 L of deionized water and the obtained product was stirred at room temperature overnight.

[Claim 5] The method for preparing improved graphene oxide according to claim 1, wherein: after the third step, the water bath is heated to 35 ° C, and the reaction system is further reacted at the temperature for 2 h.

[Claim 6] The method for preparing improved graphene oxide according to claim 1, wherein: in the fourth step, as the water is continuously added, the activity of the reactant is continuously decreased until the last added deionized water. No longer causes significant temperature changes.

[Claim 7] The method for preparing improved graphene oxide according to claim 1, wherein: in the process of adding hydrogen peroxide in the step five, the system first changes from dark brown to brown, and then to soil. Yellow, and finally turns orange.

[Claim 8] The method for preparing improved graphene oxide according to claim 1 or 7, wherein: the hydrogen peroxide in the step 5 is 25 mL and 30%, and the stirring is continued for 30 minutes.

[Claim 9] The method for producing improved graphene oxide according to claim 1, wherein the HCl solution in the step 6 is 5%.