KR20180039456A - graphene oxide powder and its manufacturing method - Google Patents

Abstract

The present invention relates to solid graphene oxide powder, and a production method thereof. To this end, the production method comprises the following steps: oxidizing graphite to form oxidized graphite; mixing the oxidized graphite with a water-soluble polymer, and dispersing and exfoliating the oxidized graphite through a cation-phi interaction to form a cation-reactive graphene oxide dispersion solution; lyophilizing the cation-reactive graphene oxide dispersion solution to form solid oxide graphene powder exhibiting high purity and less defects while having an oxygen functional group on a surface. By producing the graphene oxide with high purity and less defects using a Brodie method, it is possible to increase the dispersion stability of the graphene oxide through the lyophilization of the water-soluble polymer and the cation-phi interaction, thereby enabling mass-production.

Description

TECHNICAL FIELD The present invention relates to a graphene oxide powder and its manufacturing method,

More particularly, the present invention relates to a graphene oxide graphene grains having a high purity and a low defect density by using the Brody method, And a method for producing the grafted oxide graphene grains which can increase the dispersion stability of graphene oxide having a low defect and can be mass-produced.

Graphene is a semi-metallic substance with a thickness of one atom, in which carbon atoms are arranged in hexagonal shape by sp ² bonds in two dimensions. Such graphene can be obtained by peeling a layer of graphene from graphite. Recently, graphene sheet was peeled off and its characteristics were evaluated. As a result, it is known that when the electron mobility is more than 50,000 cm ² / Vs, the velocity is similar to that of the light flowing at zero mass. Graphene is also structurally and chemically stable, has excellent thermal conductivity characteristics, and is made of only carbon, which is a relatively light element, which makes it easy to process 1-dimensional or 2-dimensional nanopatterns. In addition, graphene sheet is an inexpensive material and has excellent price competitiveness compared to existing nanomaterials. Due to these electrical, structural, chemical, and economic properties, Grapin is expected to replace silicon-based semiconductor technology, electric and electronic devices for energy, and it can be applied to flexible electronic devices due to its excellent mechanical properties. It is expected.

Despite these excellent properties, graphene has not been developed for mass synthesis and high concentration dispersion of high quality graphene, so research on practical applications is very limited. (W. Hummers et al., J. Am. Chem. Soc., 80, 1339, 1958), the Brody method (BC Crodie Ann. Chim. Phys., 59, 466- The graphene film obtained by chemically and mechanically treating graphite crystals using a stoichiometric method (L. Staudenmaier, Ber, Dtsch. Chem. Ges., 31, 1481-1499, 1898) Is a process directly applicable to printing electronic fields such as spray, dip coating, spin coating, screen printing, ink jet printing, pad printing, knife coating, kiss coating and gravure coating. However, it is difficult to mass-produce paste by high-quality graphene dispersion solution and high concentration. This is because it is difficult to mass-produce the graphene graphene which is essential in the process of manufacturing high quality graphene. In addition, since the hydrophilic graphene oxide dispersion solution becomes hydrophobic during the reduction process, aggregation phenomenon appears in the solvent. In particular, in the case of oxidized graphene oxide having high conductivity, aggregation in the solvent is increased. In order to mass-produce such high-quality oxidized graphene reductants, it is essential to mass-produce high-quality oxidized graphene having an initial low defectivity and low oxidation degree. For this purpose, it is necessary to prepare solid form and foam. Also, a process is required to induce uniform dispersion in the production of high conductivity graphene ink and paste.

Generally, a method of producing graphene includes a process of dispersing the graphene in an aqueous solution after formation of the graphite oxide, and a process of reducing the graphene oxide. The oxidized graphene is formed through peeling using an ultrasonic grinder. However, various defects formed during acid treatment and ultrasonic pulverization and oxygen-containing functional groups are non-conductive because they are present on the surface of graphene. In order to solve this problem, a reduced graphene oxide is produced through chemical and thermal reduction. However, even when graphene restores conductivity, conductivity is greatly reduced due to various oxygen functions and defects. Also, the oxidized graphene reducer is changed from hydrophilic to hydrophobic, and formation of a precipitate due to agglomeration in the solvent is an obstacle to formation of a high concentration dispersed solution.

Recently, researches on the production of high-conductivity oxide graphene reducer and high-quality oxide graphene in large quantities for the application of printing process for flexible electric, electronic device and flexible energy storage device have been recently actively conducted. Rod Rouoff, professor at Texas Austin University in the United States, is studying the formation of graphene dispersion solution through a wet process. In the case of graphene oxide, which is used as a base material for the production of highly conductive graphene inks and pastes, a strong acid peeling method is used. However, when a strong acid is used, defects and oxidizability of the oxidized graphene are increased, and when the weak acid is used, the detachment of the oxidized graphene is not easy and a multi-layered oxidized graphene is formed. In addition, the less interaction with the oxygen functional group dispersed because the low-defect, high-purity oxidized yes revealed much as in this case hexagonal sp ² region of the pin is relatively easy to avoid. In order to overcome this problem, a new dispersion concept of acid treatment, exfoliation and high quality oxide graphene is needed.

Accordingly, an object of the present invention is to provide a process for producing a high-purity and low-defect oxide graphene by the Brody method, a freeze-drying of the water-soluble polymer and an oxidation- And a method for producing the same.

The above-mentioned object is achieved by a method of manufacturing a semiconductor device, comprising: oxidizing graphite to form oxidized graphite; Mixing the oxidized graphite with a water-soluble polymer, and dispersing and peeling the oxidized graphite through cation-phi interaction to form a cation-reactive oxidized graphene dispersion solution; And lyophilizing the cationic reactive oxidation graphene dispersion solution to form an oxide graphene solid component having an oxygen functional group on the surface thereof.

Here, the step of forming the cation-reactive oxidative graphene dispersion solution may include mixing the oxidized graphite with an alkali solvent and a water-soluble polymer, and dispersing and peeling the oxidized graphite to form a graphene oxide dispersion solution; By positioning the cation at the center of the arrangement in which the carbon atoms are linked two-dimensionally by sp ² bonds in the graphene oxide dispersion solution, the cation reaction through the cation-phi interaction between the cation and the p ² structure of the sp ² region And forming a graphene oxide dispersion solution.

Alternatively, the step of forming the cation-reactive oxidative graphene dispersion solution may include the steps of mixing the oxidized graphite with an alkali solvent and dispersing and peeling the oxidized graphite to form a graphene dispersion solution; By positioning the cation at the center of the arrangement in which the carbon atoms are linked in the two-dimensional phase by the sp ² bond in the graphene oxide dispersion solution, the cation-phi interaction with the cation structure of the cation and the p structure of the sp ² region, To form a cationic-reactive oxidative graphene dispersion solution.

The step of forming the oxidized graphite may include a step of acid-treating the graphite through the Brody method to form oxidized graphite, and the step of lyophilizing to form a grafted oxide graphene having an oxygen functional group on the surface thereof comprises: Is preferably performed at -100 to -270 ° C.

The above-mentioned object is also achieved by a method for producing a cationic electrodeposited graphene dispersion, which comprises mixing a graphite oxide with a water-soluble polymer, dispersing and peeling the oxidized graphite through a cation-phi interaction to form a cation- Which is formed by freeze-drying, by grafting an oxide graphene solid having an oxygen functional group on its surface.

According to the constitution of the present invention described above, it is possible to produce high-purity and low-defect graphene oxide grains by the Brody method, increase the dispersion stability of the graphene oxide through the lyophilizing of the water-soluble polymer and the cation- Can be obtained.

FIG. 1 is a flow chart of a method for manufacturing a solid oxide graphene blade according to an embodiment of the present invention,
Figure 2 is a flow chart showing the cation-pi interaction,
3 is a SEM photograph of a solid oxide graphene solid particle powder and a flowchart of a solid oxide graphene solid particle production method,
4 is an XPS graph of Hummus oxidized graphene, Brody oxidized graphene, and exemplary oxidized graphene,
FIG. 5 is a TGA graph of graphite, Hummus oxide graphene and an example oxide graphene,
6 is an SEM photograph of Hummus oxide graphene and Example oxide graphene,
FIG. 7 is a graph showing resonance Raman spectroscopy measurement according to the embodiment oxide graphene. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, referring to the drawings, an oxide graphene solid particle having an oxygen functional group on a surface thereof according to an embodiment of the present invention and a method for producing the same will be described in detail.

As shown in FIG. 1, graphite is first oxidized to form oxidized graphite (S1).

Powdered graphite oxide powders are synthesized from powdery graphite flakes. The oxidized graphite powder is obtained by synthesizing high-purity graphite flakes of 99.9995% in powder form by acid treatment, and then removing impurities by repeatedly washing the aqueous solution and using a centrifugal separator. The acid treatment is carried out by adding sodium chloride (NaClO ₄ ) or potassium permanganate (KMnO ₄ ) to strong acid such as fuming nitric acid or sulfuric acid to high purity graphite flake and stirring for 48 hours at room temperature . After neutralization using distilled water, filtering and washing are repeated. The oxidized graphite solution is subjected to a drying process to obtain graphite oxide powder using grinding.

The acid treatment can be carried out using a commonly used stoichiometric method (L. Staudenmaier, Ber. Dtsch. Chem. Gas., 31, 1481-1499, 1898), Hummus method (W. Hummers et al., J. Am. Chem (Brodie Ann., Chim., Phys., 59, 466-472, 1860) rather than the Brody method (Soc., 80, 1339, 1958). The oxidized graphite flakes obtained via the Hummus method are used in most cases by the Hummus method for the production of oxidized graphenes, since subsequent peeling is more likely to occur. However, the Hummus method is disadvantageous in that the removal of the oxidized graphite results in a rather high purity due to the presence of a large number of oxidizing functional groups instead of the peeling of the oxidized graphite, thereby deteriorating the quality of the oxidized graphene. On the other hand, in the case of the Brody method, it is difficult to peel off the graphite oxide, but the produced graphene grapn has the advantage of being excellent in quality with high purity and low defectiveness. Therefore, in the present invention, graphene oxide is prepared by using the Brody method instead of the commonly used Hummus method.

The oxidized graphite is mixed with a water-soluble polymer, and the oxidized graphite is dispersed and separated to form an oxidized graphene dispersion solution (S2).

The oxidized graphite powder prepared in the step S1 is dispersed in a solvent to prepare a graphite oxide dispersion solution, a water-soluble polymer is added to the dispersion solution, the oxidized graphite and the water-soluble polymer are mixed, and the oxidized graphite is peeled to form an oxidized graphene dispersion solution.

The alkali solvent is preferably an aqueous solution of sodium hydroxide (NaOH), an aqueous solution of potassium hydroxide (KOH), an aqueous solution of ammonium hydroxide (NH ₄ H), an aqueous solution of lithium hydroxide (LiOH) Ca (OH) ₂ ), and mixtures thereof. The pH of the solvent can be dispersed from 8 or more, and the most preferable pH is 10 or more.

A water-soluble polymer is added to the oxidized graphite dispersion solution and mixed. The addition of the water-soluble polymer is preferably added during the peeling of the graphene oxide, but may be added in the course of the cation-phi interaction, which is the step S3 after the graphene oxide peeling.

The water-soluble polymer may be at least one selected from the group consisting of polyvinyl alcohol, polyethylene glycol, polyethyleneimine, polyamideamine, polyvinyl formamide, polyvinyl acetate, But are not limited to, polyacrylamide, polyvinylpyrrolidone, polydiallydimethylammonium chloride, polyethylene oxide, polyacrylic acid, polystyrenesulfonic acid, polysilicic acid, polyphosphoric acid, polyethylenesulfonic acid, poly-3-vinyloxypropane-1-sulfonic acid, poly-4- Poly-4-vinylphenol, poly-4-vinylphenyl sulfuric acid, polyethyleneohosphoric acid, poly Polymaleic acid, poly-4-vinylbenzoic acid, methyl cellulose, hydroxy ethyl cellulose, carboxy methyl cellulose, sodium carboxymethyl cellulose, It is preferably selected from the group consisting of sodium carboxy methyl cellulose, hydroxy propyl cellulose, sodium carboxymethylcellulose, polysaccharide, starch, and mixtures thereof.

Dispersion and exfoliation of the oxidized graphite are carried out by using at least one of sonication, homogenizer and high pressure homogenizer in the oxidized graphite dispersion solution mixed with the water-soluble polymer. In this case, the time required for dispersion and peeling is 10 minutes to 5 hours. If it is less than 10 minutes, dispersion and peeling can not be performed smoothly. If the treatment is performed for more than 5 hours, defect formation is increased and high quality oxide graphene is obtained none.

The graphene oxide graphene dispersion solution is formed by cation-phi interaction through the cation-reactive graphene graphene dispersion solution (S3).

The dispersed and separated graphene oxide dispersion solution is subjected to cation-phi interaction to form a cationic-reactive oxide graphene dispersion solution. The cationic reaction oxidative graphene dispersion solution can be obtained by maintaining the reaction time of the oxidized graphene dispersion solution at room temperature for 1 minute to 10 hours in the state where no external physical force such as ultrasonic pulverization is applied. Here, the concentration of the graphene oxide dispersion solution can be obtained by maintaining the reaction time in the range of 1 mg / L to 50 g / L at room temperature for about 10 minutes. If the concentration of the graphene dispersion solution is less than 1 mg / L, it is difficult to form a high concentration graphene grains. If the concentration range of the graphene oxide dispersion solution is more than 50 g / L, the graphene grains are aggregated .

This reaction is carried out in the presence of sodium (Na ⁺ ), potassium (K ⁺ ), ammonium (NH ₄ ⁺ ), lithium (Li ⁺ ), calcium Ca as that ^{2 +)} and activate the same cation as the reaction of the hexagonal sp ² pie structure of the region, the holding of the reaction time for interaction with the graphene oxide with about reduction of the alkaline solvent is removed in an oxygen functional group and cationic As shown in FIG. 2 shows that the added solvent is an aqueous solution of sodium hydroxide and the cation is a sodium ion.

The cationic-reactive oxidative graphene dispersion solution may be prepared by a solvent volatilization method such as a rotary evaporation method, a centrifugal separation method, an agitation method, or the like in order to activate the cation-phi interaction. This removes the local oxidation function by controlling the temperature and time in order to further increase the hexagonal sp ² region of the graphene through which the cation can adsorb through the weak reduction. By evaporating the water using the solvent volatilization method, the cation-phi interaction is activated and a highly concentrated dispersion solution is prepared.

The cationic graphene graphene dispersion solution is lyophilized to form a solid oxide graphene having oxygen functional groups on its surface (S4).

The cationic oxidative graphene dispersion solution uniformly dispersed in the alkali solvent and the water-soluble polymer is lyophilized to form a solid oxide graphene having oxygen functional groups on its surface. Freeze-drying is performed using liquefied nitrogen at -100 to -270 ° C for 10 to 60 minutes, and then it is dried at 10 ^-3 torr for 1 to 24 hours.

Here, the shape of the end portion of the oxide graphene solid particles is formed in a form in which the pores are randomly formed and do not aggregate with each other as shown in FIG. Such a structure is a structure in which a cationic oxidized graphene dispersion solution is mixed with an alkali solvent containing water and a water-soluble polymer. That is, since the alkali solvent and the water-soluble polymer are different from each other in freezing point, they are not uniformly freezed, and when they are freeze-dried, they are not uniform and random pores are formed. Since the graphene grains formed with pores through freeze-drying do not aggregate in the state of being peeled and become solid-state in the form of solid particles, unlike conventional graphene grains, they do not coalesce and because of the Brody's method, Can be obtained.

In the case of the present invention, even if a large amount of low-defect and high-purity oxidized graphene is produced, it can be produced so as to maintain dispersion stability without being clumped together. In the state where a large amount of oxidized graphene is prepared and stored, The graphene reduction material can be used by being taken out immediately or by reducing the graphene oxide. That is, there is an advantage that high-quality, high-concentration graphene grains can be easily used according to a user's desired use. Such an oxide graphene is an oxide graphene having an oxygen functional group on its surface. In general, a graphene oxide particle is not a graphene oxide but a graphene oxide reduced material is distributed. Since oxidized graphene reduced material has no oxygen functional group on the surface thereof, the mass-producible oxidized graphene of the present invention has an oxygen functional group on its surface. Therefore, the final material and the purpose of use differ from the reduced oxidized graphene Do.

Hereinafter, embodiments of the present invention will be described in more detail.

<Examples>

First, 10 g of pure graphite (purity 99.9995%, -200 mesh, made by Alfar Aesar), 350 ml of fuming nitric acid and 74 g of sodium chloride oxide are sequentially mixed at 37 g in a room temperature. The mixture was stirred for 48 hours, subjected to an acid treatment using the Brody method, and then subjected to neutralization, washing, filtration, cleaning and drying to obtain graphite oxide powder. The prepared graphite oxide powder was prepared by adding potassium hydroxide aqueous solution of pH 10 in which potassium hydroxide (KOH) was dissolved at a concentration of 300 mg / L and carboxy methyl cellulose as a water-soluble polymer and stirring the mixture to prepare a graphite oxide dispersion solution. Then, ultrasonic waves were applied to the oxidized graphite dispersion solution for 1 hour to prepare a homogeneous dispersion solution of graphene oxide. Thereafter, a cationic graphene dispersion solution is prepared by maintaining at least one hour so that the physical properties of the graphene graphene dispersion solution are stably discharged at room temperature in order to apply the cation-phi interaction. Thereafter, the cationic graphene graphene dispersion solution was lyophilized for 10 hours or longer to remove the aqueous potassium hydroxide solution and the water-soluble polymer, thereby obtaining an oxide graphene solid portion having oxygen functional groups on the surface (FIGS.

The analytical graph of the graphene oxide solid particles prepared through these examples and the analysis graph of the comparative example will be described as follows. FIG. 4 is a graph showing X-ray photoelectron spectroscopy (XPS) measurements of oxidized graphene grains using the commonly used hummus method, oxidized graphene using the Brody method, and oxidized graphene according to the embodiment of the present invention. In the case of Hummus oxide graphene, it can be seen that the numerical value of the oxidizing group (C-O) shown in blue is high. In contrast, Brody's oxide graphene is lower than Hummers' oxide graphene. When the number of oxidizing functional groups is large, defects of the oxide graphene are large and the purity is decreased. That is, graphene oxide with many oxidizing functional groups can not be regarded as high quality graphene oxide. On the contrary, it can be seen that the oxidation graphene according to the embodiment of the present invention has a much lower oxidizing group value than that of conventional Hummus oxide graphene and Brody oxide graphene. That is, high quality graphene grains with low defects and high purity can be obtained.

FIG. 5 is a graph of graphite, Hummers-GO, and exemplary oxide graphene (Example-GO) through thermogravinetry analysis (TGA) measurements. This means that the weight of each sample when heated increases with the temperature, which means that as the weight decreases, the sample burns. The fact that the sample burns at low temperatures means that there are many oxidizing groups, which means that the quality of the oxidized graphene is poor. In the case of graphite, since there are no oxidizing functional groups, it can be confirmed that weight reduction is hardly observed at temperatures lower than 800 ° C. On the other hand, in the case of Hummus oxide graphene and the example oxide graphene, burning occurs at a temperature lower than that of graphite because it has an oxidizing functional group, and in particular, Hummers oxide graphene Is decreased. This means that the embodiment graphene graphene is a high-purity, low-defect graphene graphene than Hummus oxidized graphene.

The same experiment was also carried out on oxidized graphene reductions obtained by reducing oxidized graphene. The graphite showed almost no weight loss at less than 800 DEG C, and the graphene oxide graphene reduction of the example (Example-rGO) showed almost no weight loss at a level similar to graphite to less than about 700 DEG C I could confirm. On the other hand, the Hummers oxide graphene reduction (Hummers-rGO) decreased in weight at a lower temperature than the oxidized graphene reductions of the Examples, It means that the defects are more defective than the reduced ones and the purity is not high.

FIG. 6 is a SEM (scanning electron microscope) photograph of Hummers oxide grains (Hummers GO) and Example oxide grains (Example GO). The graphene grains produced by conventional methods are small in area and poor in crystallinity. On the other hand, as shown in the SEM photograph, the oxide graphene of Example has a large area of graphene grains and has low defect and high purity characteristics.

FIG. 7 is a graph of a resonance Raman spectroscopy measurement according to an embodiment of the present invention, which means that the crystallinity of the oxidized graphene is improved. This is because the D / G ratio of CIRGO, which is a sample through cation exchange interaction during the reduction process, is smaller in the preparation of oxidized graphene reduction product. This means that there are fewer defects than the existing RGO. It also means that the 2D / G ratio can reach closer to that of graphene after reduction.

As described above, the graphene oxide solid content having oxygen functional groups on the surface prepared by using the method for preparing a graphene oxide graphene solid solution according to the present invention is characterized in that graphene oxide grains having high purity and low defectivity Can be obtained. In addition, since the dispersion solution containing the water-soluble polymer is freeze-dried to obtain a solid structure having a porous structure, the dispersion stability of the oxidized graphene is enhanced through the cation-phi interaction, It is possible to obtain an evenly dispersed oxide graphene. In particular, since the graphene oxide is produced so as to be evenly dispersed, it has an advantage that it is easy to mass-produce the graphene oxide having an oxygen functional group on its surface.

Claims (11)

In the method for producing a graphene oxide graphene solid,
Oxidizing the graphite to form oxidized graphite;
Mixing the oxidized graphite with a water-soluble polymer, and dispersing and peeling the oxidized graphite through cation-phi interaction to form a cation-reactive oxidized graphene dispersion solution;
And lyophilizing the cationic-reactive oxidative graphene dispersion solution to form an oxide graphene solid component having an oxygen functional group on its surface. The method according to claim 1,
The step of forming the cationic reactive oxidation graphene dispersion solution comprises:
Mixing the oxidized graphite with an alkali solvent and a water-soluble polymer, and dispersing and peeling the oxidized graphite to form an oxidized graphene dispersion solution;
By positioning the cation at the center of the arrangement in which the carbon atoms are linked two-dimensionally by sp ² bonds in the graphene oxide dispersion solution, the cation reaction through the cation-phi interaction between the cation and the p ² structure of the sp ² region To form a graphene oxide dispersion solution. &Lt; RTI ID = 0.0 &gt; 8. &lt; / RTI &gt; 3. The method of claim 2,
The alkaline solvent is sodium hydroxide (NaOH) aqueous solution, potassium hydroxide (KOH) solution, ammonium hydroxide (NH ₄ OH) solution, lithium hydroxide (LiOH) solution, calcium hydroxide (Ca (OH) ₂₎ from the group consisting of aqueous solution, and mixtures thereof By weight based on the total weight of the graphene grains. 3. The method of claim 2,
The step of forming the oxidized graphene dispersion solution comprises:
Wherein the oxidized graphite is dispersed and peeled by using at least one of ultrasonic pulverization, homogenizer and high-pressure homogenizer in the oxidized graphite dispersion solution. The method according to claim 1,
The step of forming the cationic reactive oxidation graphene dispersion solution comprises:
Mixing the oxidized graphite with an alkaline solvent and dispersing and peeling the oxidized graphite to form an oxidized graphene dispersion solution;
By positioning the cation at the center of the arrangement in which the carbon atoms are linked in the two-dimensional phase by the sp ² bond in the graphene oxide dispersion solution, the cation-phi interaction with the cation structure of the cation and the p structure of the sp ² region, To form a cationic-reactive oxidative graphene dispersion solution. The method according to claim 1,
The step of forming the oxidized graphite may include:
Wherein the graphite is subjected to acid treatment through the Brody method to form oxidized graphite. The method according to claim 6,
Wherein the acid treatment is performed by using fuming nitric acid or sulfuric acid in the graphite. The method according to claim 1,
The water-soluble polymer may be at least one selected from the group consisting of polyvinyl alcohol, polyethylene glycol, polyethyleneimine, polyamideamine, polyvinyl formamide, polyvinyl acetate, poly But are not limited to, polyacrylamide, polyvinylpyrrolidone, polydiallydimethylammonium chloride, polyethylene oxide, polyacrylic acid, polystyrenesulfonic acid, polysilicic acid, polysilicic acid, polyphosphoric acid, polyethylenesulfonic acid, poly-3-vinyloxypropane-1-sulfonic acid, poly-4-vinyl Poly-4-vinylphenol, poly-4-vinylphenyl sulfuric acid, polyethyleneohosphoric acid, Poly-4-vinylbenzoic acid, methyl cellulose, hydroxy ethyl cellulose, carboxy methyl cellulose, sodium carboxymethyl cellulose, Characterized in that it is selected from the group consisting of sodium carboxy methyl cellulose, hydroxy propyl cellulose, sodium carboxymethylcellulose, polysaccharide, starch and mixtures thereof. Method for manufacturing fin solid particles. The method according to claim 1,
The step of lyophilizing to form a solid oxide grains having an oxygen functional group on the surface thereof,
Characterized in that it is carried out at -100 to -270 캜 using liquefied nitrogen. At the end of graphene oxide grains,
Mixing the oxidized graphite with a water-soluble polymer, dispersing and peeling the oxidized graphite through cation-phi interaction to form a cation-reactive oxidized graphene dispersion solution, and lyophilizing the cation-reactive oxidized graphene dispersion solution Characterized by graphene oxide solids with oxygen functional groups on the surface. At the end of graphene oxide grains,
A graft oxide graft having an oxygen functional group on its surface, characterized in that it is produced through at least one of the following items 1 to 9.

Images