阅读说明：本技术 一种石墨烯的制备方法及其设备 (Preparation method and equipment of graphene ) 是由 吕文建 杨学权 张寅强 孙建国 许威 李书东 袁亚雄 吕东平 徐康 陈冬 于 2020-12-16 设计创作，主要内容包括：本发明涉及石墨烯制备技术领域,尤其为一种石墨烯的制备方法及其设备,包括如下步骤：取石墨进行粉碎和研磨制得石墨粉,将石墨粉和去离子水倒入搅拌设备的内部进行预先搅拌,同时向搅拌设备的内部添加50％-60％硝酸溶液搅拌20-30min,然后加入35％-75％重铬酸钾溶液进行氧化反应,反应时间为50-60min,反应后制得氧化石墨悬浮液；本发明能够在制备石墨烯的过程中增加石墨烯的导电性,并弥补石墨烯材料在氧化还原法制备过程中损失的电学性能,同时扩大石墨烯材料的应用范围,解决了目前在氧化还原法制备石墨烯的过程中,由于反应造成石墨烯的结构出现缺陷,导致石墨烯材料的导电性能下降,并造成石墨烯材料的应用受到限制的问题。(The invention relates to the technical field of graphene preparation, in particular to a preparation method and equipment of graphene, which comprises the following steps: crushing and grinding graphite to obtain graphite powder, pouring the graphite powder and deionized water into stirring equipment for pre-stirring, adding 50-60% nitric acid solution into the stirring equipment for stirring for 20-30min, adding 35-75% potassium dichromate solution for oxidation reaction for 50-60min, and obtaining graphite oxide suspension after reaction; according to the invention, the conductivity of the graphene can be increased in the process of preparing the graphene, the loss electrical property of the graphene material in the preparation process of the oxidation-reduction method can be compensated, the application range of the graphene material can be expanded, and the problems that the conductivity of the graphene material is reduced and the application of the graphene material is limited due to the fact that the graphene structure is defective due to reaction in the existing process of preparing the graphene by the oxidation-reduction method are solved.)

1. A preparation method of graphene is characterized by comprising the following steps: the method comprises the following steps:

s1, crushing and grinding graphite to obtain graphite powder, pouring the graphite powder and deionized water into stirring equipment for pre-stirring, adding 50-60% nitric acid solution into the stirring equipment for stirring for 20-30min, adding 35-75% potassium dichromate solution for oxidation reaction for 50-60min, and obtaining graphite oxide suspension after reaction;

s2, filtering the graphite oxide suspension liquid prepared in the step (S1) to obtain a graphite oxide solid substance, washing the graphite oxide solid substance by using deionized water, and drying the washed graphite oxide solid substance at 50-100 ℃ to obtain pure graphite oxide powder;

s3, putting the graphite oxide powder obtained in the step (S2) into pure water to prepare a solvent, then placing the graphite oxide powder solvent into ultrasonic dispersion equipment, and then carrying out ultrasonic dispersion on the graphite oxide powder solvent to prepare a graphene oxide solvent;

s4, adding 45% -60% of sodium borohydride solution into the solvent obtained in the step (S3), stirring, reacting for 0.5-1.5h at the temperature of 30-60 ℃, and obtaining graphene suspension after the reaction is finished;

and S5, adding a conductive additive into the graphene suspension liquid obtained in the step (S4), stirring, taking out the solid in the stirring container after stirring for 1-2h, and filtering and drying the solid to obtain the finished graphene powder.

2. The method for preparing graphene according to claim 1, wherein: in the step (S1), after the graphite is pulverized and ground, the graphite powder is screened.

3. The method for preparing graphene according to claim 1, wherein: in the step (S1), the pre-stirring time is 10-15min, and the stirring rotation speed is 1000-1300 r/min.

4. The method for preparing graphene according to claim 1, wherein: in the step (S2), the PH of the ionized water after rinsing is measured during rinsing, and when the PH of the ionized water is 6 to 7, the rinsing is stopped.

5. The method for preparing graphene according to claim 1, wherein: in the step (S3), the time of ultrasonic dispersion is 0.5-1 h.

6. The method for preparing graphene according to claim 1, wherein: in the step (S4), after the reaction is completed, the graphene suspension is cooled, and simultaneously, pure water is added to adjust the PH of the graphene suspension to 7.

7. The method for preparing graphene according to claim 1, wherein: in the step (S5), the conductive additive is graphite conductive additive, and the stirring speed is 2000-3000/min.

8. The graphene preparation apparatus according to any one of claims 1 to 7, comprising a stirring reaction kettle (1) and an ultrasonic dispersion stirrer (2), wherein: one side of the stirring reaction kettle (1) is connected with a filtering tank (3), the other side of the filtering tank (3) is connected with a cleaning tank (4), and the other side of the cleaning tank (4) is connected with a dryer (5).

Technical Field

The invention relates to the technical field of graphene preparation, in particular to a preparation method and equipment of graphene.

Background

The graphene is a two-dimensional honeycomb-shaped lattice material formed by tightly combining planar single-layer carbon atoms, and the special structure enables the graphene to have the properties of high specific surface area, high mechanical strength, chemical stability and the like, and the carbon atoms in the more important graphene are subjected to sp2 hybridization, so that electrons of the remaining p orbit are contributed to form a large pi bond, and pi electrons can freely move, so that the graphene has good electrical conductivity, a novel quantum Hall effect and unique superconductivity. The excellent electrical properties of the graphene attract the attention of researchers at home and abroad on the application of the graphene in conductive materials, and the graphene has wide application prospects in the aspects of nano electronic devices, composite materials, solar cells, supercapacitors, hydrogen storage materials and the like due to the unique structure and the excellent electrical, thermal and mechanical properties of the graphene. Compared with film-shaped and powder-shaped graphene, the flocculent graphene has larger specific surface area and surface performance, looser pore structure and surface structure, and has larger application value in the fields of super capacitors, adsorption, catalyst carriers and the like.

At present, the method adopted for preparing graphene comprises the following steps: a micro mechanical lift-off method, a chemical vapor deposition method, a redox method, a solvent lift-off method, a solvothermal method, and the like. The redox method is always considered to be an effective way for producing graphene in a simple and reliable manner and in a large scale, but the redox method can cause topological defects of five-membered rings, seven-membered rings and the like of graphene or structural defects of-OH groups, which can cause the loss of partial electrical properties of graphene, reduce the electrical conductivity of the graphene material and limit the application of the graphene material.

Disclosure of Invention

The invention aims to provide a preparation method of graphene and equipment thereof, which can increase the conductivity of the graphene in the process of preparing the graphene, make up the electrical property loss of a graphene material in the preparation process of a redox method, expand the application range of the graphene material, and solve the problems that the conductivity of the graphene material is reduced and the application of the graphene material is limited due to the defect of the graphene structure caused by reaction in the conventional process of preparing the graphene by the redox method.

In order to achieve the purpose, the invention provides the following technical scheme: a preparation method of graphene comprises the following steps:

s1, crushing and grinding graphite to obtain graphite powder, pouring the graphite powder and deionized water into stirring equipment for pre-stirring, adding 50-60% nitric acid solution into the stirring equipment for stirring for 20-30min, adding 35-75% potassium dichromate solution for oxidation reaction for 50-60min, and obtaining graphite oxide suspension after reaction;

s2, filtering the graphite oxide suspension liquid prepared in the step (S1) to obtain a graphite oxide solid substance, washing the graphite oxide solid substance by using deionized water, and drying the washed graphite oxide solid substance at 50-100 ℃ to obtain pure graphite oxide powder;

s3, putting the graphite oxide powder obtained in the step (S2) into pure water to prepare a solvent, then placing the graphite oxide powder solvent into ultrasonic dispersion equipment, and then carrying out ultrasonic dispersion on the graphite oxide powder solvent to prepare a graphene oxide solvent;

s4, adding 45% -60% of sodium borohydride solution into the solvent obtained in the step (S3), stirring, reacting for 0.5-1.5h at the temperature of 30-60 ℃, and obtaining graphene suspension after the reaction is finished;

and S5, adding a conductive additive into the graphene suspension liquid obtained in the step (S4), stirring, taking out the solid in the stirring container after stirring for 1-2h, and filtering and drying the solid to obtain the finished graphene powder.

Preferably, in the step (S1), after the graphite is pulverized and ground, the graphite powder is screened.

Preferably, in the step (S1), the pre-stirring time is 10-15min, and the stirring rotation speed is 1000-1300 r/min.

Preferably, in the step (S2), the PH of the ionized water after rinsing is measured during rinsing, and the rinsing is stopped when the PH of the ionized water is 6 to 7.

Preferably, in the step (S3), the ultrasonic dispersion time is 0.5 to 1 hour.

Preferably, in the step (S4), after the reaction is completed, the graphene suspension is cooled, and at the same time, pure water is added to adjust the PH of the graphene suspension to 7.

Preferably, in the step (S5), the conductive additive is a graphite conductive additive, and the stirring speed is 2000-3000/min.

The utility model provides a preparation equipment of graphite alkene, includes stirring reation kettle and supersound dispersion mixer, one side of stirring reation kettle is connected with the filtering ponds, the opposite side of filtering ponds is connected with washs the pond, the opposite side of wasing the pond is connected with the drying-machine.

Compared with the prior art, the invention has the following beneficial effects:

1. according to the invention, the conductivity of the graphene can be increased in the process of preparing the graphene, the loss electrical property of the graphene material in the preparation process of the oxidation-reduction method can be compensated, the application range of the graphene material can be expanded, and the problems that the conductivity of the graphene material is reduced and the application of the graphene material is limited due to the fact that the structure of the graphene is defective due to reaction in the existing process of preparing the graphene by the oxidation-reduction method can be solved;

2. through screening the graphite powder after crushing and grinding, the method can screen the blocky graphite which is not completely crushed so as to prevent the blocky graphite from participating in reaction to cause that partial materials can not fully react and simultaneously influence the proportion of the materials and the quality of finished products, so that the preparation of graphene is influenced, through pre-stirring the ionized water and the graphite powder, the graphite powder is uniformly distributed in the ionized water so as to mix the graphite powder with the nitric acid solution and the potassium dichromate solution, the reaction is more thorough and sufficient, the quality of the finished products is improved, through washing the graphite oxide solid, the nitric acid solution or the potassium dichromate solution remained on the surface of the graphite oxide solid is removed, so that the subsequent steps can not be influenced by the nitric acid solution or the potassium dichromate solution, and meanwhile, through measuring the pH value of the washed ionized water, the ionized water can carry residual nitric acid solution and potassium dichromate solution in the washing process, determining whether residues remain on the surface of the graphite oxide solid by measuring the change of the pH value, wherein when the pH value is 7, the graphite oxide solid is completely cleaned;

3. through carrying out ultrasonic dispersion to graphite oxide, ultrasonic dispersion lets in the ultrasonic wave in the liquid, and utilize ultrasonic vibration and dispersion, make the more abundant mixture of solid-liquid, play the promotion effect to most chemical reaction, and make graphite oxide disperse into graphite oxide, make graphite oxide more even with distribute inside solution simultaneously, help graphite oxide and reductant intensive mixing, through adjusting the pH value of graphite alkene suspension to 7, it can dilute the strong acid or strong base in graphite alkene suspension, avoid strong acid or strong base to influence subsequent processing, and cause the quality of finished product to receive the influence, through the addition of graphite conductive additive, graphite conductive additive can mix the inside that gets into graphite alkene with modes such as electrochemistry or ion, and promote the electric conductive property of graphite alkene by a wide margin, through stirring reation kettle, ultrasonic dispersion mixer, a, The setting of filtering ponds, washing pond and drying-machine, stirring reation kettle is used for stirring and reacting the material, and supersound dispersion mixer is used for dispersing, stirring and reacting the material, and the filtering ponds can filter solution or suspension, and the washing pond then can wash solid material, and the drying-machine can dry the material after wasing.

Drawings

FIG. 1 is a process flow diagram of the present invention;

FIG. 2 is a schematic structural diagram of an apparatus for preparing graphene according to the present invention;

FIG. 3 is a schematic view of the structure of the ultrasonic disperser according to the present invention.

In the figure: 1. stirring the reaction kettle; 2. an ultrasonic dispersion mixer; 3. a filtration tank; 4. a cleaning tank; 5. and a dryer.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, a method for preparing graphene includes the following steps:

s1, crushing and grinding graphite to obtain graphite powder, pouring the graphite powder and deionized water into stirring equipment for pre-stirring, adding 55% nitric acid solution into the stirring equipment for stirring for 25min, adding 60% potassium dichromate solution for oxidation reaction for 50min, and obtaining graphite oxide suspension after reaction;

s2, filtering the graphite oxide suspension liquid prepared in the step (S1) to obtain a graphite oxide solid substance, washing the graphite oxide solid substance by using deionized water, and drying the washed graphite oxide solid substance at 75 ℃ to obtain pure graphite oxide powder;

s3, putting the graphite oxide powder obtained in the step (S2) into pure water to prepare a solvent, then placing the graphite oxide powder solvent into ultrasonic dispersion equipment, and then carrying out ultrasonic dispersion on the graphite oxide powder solvent to prepare a graphene oxide solvent;

s4, adding 50% sodium borohydride solution into the solvent obtained in the step (S3), stirring, reacting for 1 hour at the temperature of 50 ℃, and obtaining graphene suspension after the reaction is finished;

and S5, adding a conductive additive into the graphene suspension liquid obtained in the step (S4), stirring, taking out the solid in the stirring container after stirring for 1.5h, and filtering and drying the solid to obtain the finished graphene powder.

In this embodiment, in the step (S1), after the graphite is crushed and ground, the graphite powder is screened, and by screening the graphite powder after the crushing and grinding, it is possible to screen out blocky graphite that is not completely crushed, so as to prevent the blocky graphite from participating in the reaction, which may cause that part of the materials may not sufficiently react, and simultaneously affect the material ratio and the quality of the finished product, which may affect the preparation of the graphene.

In this embodiment, in the step (S1), the preliminary stirring time is 15min, and the stirring speed is 1300r/min, and the ionized water and the graphite powder are preliminary stirred, so that the graphite powder is uniformly distributed in the ionized water, and the graphite powder, the nitric acid solution and the potassium dichromate solution are mixed, so that the reaction is more thorough and sufficient, and the quality of the finished product is improved.

In this embodiment, in step (S2), measure the PH of the ionized water after washing in the washing process, when the PH of the ionized water is 7, stop washing, through washing the graphite oxide solid, be used for getting rid of the remaining nitric acid solution or potassium dichromate solution on the surface of the graphite oxide solid, in order to guarantee that nitric acid solution or potassium dichromate solution can not influence subsequent steps, measure the PH of the ionized water after washing simultaneously, the ionized water can carry the nitric acid solution and the potassium dichromate solution remains in the washing process, through measuring the change of the PH, be used for determining whether the graphite oxide solid surface still remains the residue, when the PH is 7, then indicate that the graphite oxide solid has been washed.

In this embodiment, in step (S3), the ultrasonic dispersion time is 0.5h, and through carrying out ultrasonic dispersion to graphite oxide, ultrasonic dispersion lets in the ultrasonic wave in the liquid to utilize the vibration and the dispersion of ultrasonic wave, make solid-liquid more abundant mix, play the promotion effect to most chemical reaction, and make graphite oxide disperse into graphene oxide, make the more even distribution of graphene oxide inside the solution simultaneously, help graphene oxide and reductant intensive mixing.

In this embodiment, in step (S4), after the reaction is finished, the graphene suspension is cooled, and simultaneously, pure water is added to adjust the PH of the graphene suspension to 7, and by adjusting the PH of the graphene suspension to 7, the strong acid or the strong base in the graphene suspension can be diluted, so that the strong acid or the strong base is prevented from affecting subsequent processes, and the quality of the finished product is prevented from being affected.

In this embodiment, in the step (S5), the conductive additive is a graphite conductive additive, and the stirring speed is 3000/min, and by adding the graphite conductive additive, the graphite conductive additive can be doped into the graphene in an electrochemical or ionic manner, and the conductivity of the graphene is greatly improved.

Please refer to fig. 2 and 3, a graphene preparation apparatus, which comprises a stirring reaction kettle 1 and an ultrasonic dispersion stirrer 2, wherein one side of the stirring reaction kettle 1 is connected with a filtering tank 3, the other side of the filtering tank 3 is connected with a cleaning tank 4, the other side of the cleaning tank 4 is connected with a dryer 5, the stirring reaction kettle 1, the ultrasonic dispersion stirrer 2, the filtering tank 3, the cleaning tank 4 and the dryer 5 are arranged, the stirring reaction kettle 1 is used for stirring and reacting materials, the ultrasonic dispersion stirrer 2 is used for dispersing, stirring and reacting the materials, the filtering tank 3 can filter solution or suspension, the cleaning tank 4 can clean solid materials, and the dryer 5 can dry the cleaned materials.

According to the invention, the conductivity of the graphene can be increased in the process of preparing the graphene, the loss electrical property of the graphene material in the preparation process of the oxidation-reduction method can be compensated, the application range of the graphene material can be expanded, and the problems that the conductivity of the graphene material is reduced and the application of the graphene material is limited due to the fact that the graphene structure is defective due to reaction in the existing process of preparing the graphene by the oxidation-reduction method are solved.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.