KR20180121048A - Preparation method for graphene oxide using ultrasonic treatment - Google Patents

Abstract

The present invention relates to a method for producing graphene oxide using ultrasound. According to the present invention, the method for producing graphene oxide enables production of graphene oxide through irradiation of ultrasound, efficiently mass-producing graphene oxide in a very short time. Graphene oxide is formed to be thin, specific surface area and crystallinity are high, and oxidation efficiency is excellent. In addition, since sodium nitrate is not used, no harmful gas is generated, which is advantageous in terms of environmental friendliness.

Description

[0001] The present invention relates to a method for preparing graphene oxide using ultrasonic waves,

The present invention relates to a method for producing graphene oxide using ultrasonic waves.

Graphene is one of the carbon materials, which is a two-dimensional thin film with a thickness of 0.34 nm which is a single layer of graphite in which carbon atoms are stacked in a honeycomb-like structure. The graphene has double bonds and is excellent in strength and electrical conductivity.

Indeed, graphene is known to deliver about 100 times more current at room temperature than copper per unit area, 100 times faster than silicon. This superior electrical conductivity has the potential to become a next-generation semiconductor material to replace silicon. In addition, it can be applied to a variety of applications such as high-efficiency composite materials including high-efficiency solar cells, super capacitors, flexible displays, and high-strength films.

Methods for producing graphene include mechanical exfoliation (1) using a scotch tape, chemical vapor deposition (CVD) (2), epitaxy synthesis (3), chemical stripping using oxidation- Law (4) and others.

In the case of the chemical peeling method, graphene peeling after graphitizing the graphite is observed. As a result, it is often seen that the graphene is not peeled off smoothly. It is.

The chemical peeling of graphene is accomplished by simple ultrasonic grinding after insertion of graphene interlayer oxygen functionalities through the production of oxidized graphite. At this time, the interlayer spacing of graphene through oxidation of graphite is increased, and the peeling is induced by reducing inter-layer π-π interaction and van der Waals force. Such a method for treating graphite oxide has a method of oxidizing graphite using a mixture of sodium nitrate and potassium chlorate in fuming sulfuric acid. However, in the above method, sodium nitrate is used to prepare graphene There is a disadvantage in that toxic gas is generated.

Japanese Patent Application Laid-Open No. 10-2016-0104430

It is an object of the present invention to provide a process for producing graphene oxide that is environmentally friendly, efficient and mass-producible.

In order to achieve the above object, the present invention provides, in one embodiment,

Comprising the step of irradiating a mixture of graphite with an acid and potassium permanganate with ultrasonic waves,

Wherein the step of irradiating the ultrasonic waves is performed at 20 to 50 DEG C for 30 minutes to 70 minutes.

The method for producing graphene oxide according to the present invention is characterized in that graphene oxide is produced by irradiating ultrasonic waves to form graphene oxide thinly and has high specific surface area and high crystallinity so that oxidation efficiency is excellent and no harmful gas is used because sodium nitrate is not used There is an advantage that it is environmentally friendly.

1 is an image obtained by scanning electron microscopy (SEM) of graphene oxide of Example 1 and Comparative Example 1 and graphite of Comparative Example 2: (a) is a graphite photograph image of Comparative Example 2, and (b) (C) is a graphene oxide photographic image of Comparative Example 1. Fig.
2 is an image of graphene oxide of Example 1 and Comparative Example 1 taken by a transmission electron microscope (TEM) and a high-resolution transmission electron microscope (HR-TEM): (a) and (b) (C) and (d) are graphs showing the graphene oxides of Example 1 and Comparative Example 1, respectively, by a high-resolution transmission electron microscope (HR-TEM), and the graphene oxides of Comparative Example 1 were photographed by a transmission electron microscope .
3 is a graph of X-ray diffraction analysis (XPS) of the graphene oxide of Example 1 and Comparative Example 1 and the graphite of Comparative Example 2;
4 is a result of X-ray photoelectron spectroscopy (XPS) of graphite oxide of Example 1 and Comparative Example 1 and graphite of Comparative Example 2. Fig.
5 is a graph of Fourier Transform-Infrared Spectroscopy (FT-IR) measurement of graphene oxide of Example 1 and Comparative Example 1 and graphite of Comparative Example 2. FIG.
FIG. 6 is a graph showing the UV-visible absorbance of a graphene oxide of Example 1 and Comparative Example 1 and a graphite of Comparative Example 2 measured using a UV-Vis pectrophotometer. FIG.
7 is a graph showing the Raman spectrum of the graphite of Example 1 and Comparative Example 1 and the graphite of the graphite of Comparative Example 2: (a) shows the Raman spectrum of the graphite of Comparative Example 2, (b) (C) shows the Raman spectrum of the graphene oxide of Comparative Example 1, and (d) shows the 2D Raman spectrum of the graphene oxide of Example 1 and Comparative Example 1 Can be confirmed.
8 is a graph showing the results of thermogravimetric analysis of graphene oxide of Example 1 and Comparative Example 1 and graphite of Comparative Example 2. Fig.

The present invention relates to a method for producing graphene oxide which is thin and has a large specific surface area and high crystallinity by using ultrasonic waves and is excellent in oxidation efficiency.

Graphene is a two - dimensional allotropic carbon with honeycomb - shaped hexagonal lattice as a layer of carbon atoms. It has unique properties and excellent electrical and physical properties and has been actively studied for many years. Methods for producing graphene include a method of separating a graphene layer from a graphite crystal and a chemical vapor deposition method of synthesizing graphene using a transition metal that adsorbs carbon well at a high temperature as a catalyst layer, The epitaxial growth method in which carbon was grown along the surface texture is being studied. Particularly, the chemical peeling method in which graphite is oxidized and separated in a solution state and then reduced is subjected to a great deal of research due to the possibility of mass production and easy chemical modification and hybridization with other materials. However, in the chemical stripping method, there is a method of oxidizing graphite by using a mixture of fuming sulfuric acid and sodium nitrate and potassium chlorate. However, in the case of using sodium nitrate, Toxic gas is generated.

Accordingly, the present invention provides a process for producing graphene oxide that is eco-friendly, efficient, and mass-producible.

The method for producing graphene oxide according to the present invention is characterized in that graphene oxide is produced by irradiating ultrasonic waves to form graphene oxide thinly and has high specific surface area and high crystallinity so that oxidation efficiency is excellent and no harmful gas is used because sodium nitrate is not used There is an advantage that it is environmentally friendly.

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

In one embodiment,

Comprising the step of irradiating a mixture of graphite with an acid and potassium permanganate with ultrasonic waves,

Wherein the step of irradiating the ultrasonic waves is performed at 20 to 50 DEG C for 30 minutes to 70 minutes.

The method for producing graphene oxide according to the present invention is characterized in that the mixture of graphite and potassium permanganate is irradiated with ultrasound to penetrate into graphite in which an acid and potassium permanganate are stacked to form an excellent graphite oxidation efficiency, Oxidation and peeling of the graphite proceed at the same time, which is advantageous in that the production method is simple. Thus, the present invention does not use any additive such as sodium nitrate to increase the efficiency of graphite oxidation and exfoliation, so that no harmful gas is generated, which is eco-friendly.

As one example, the step of irradiating ultrasonic waves in the present invention may be performed at a temperature of 20 to 50 占 폚, 25 to 45 占 폚 or 30 to 40 占 폚 for 30 to 70 minutes, 35 to 65 minutes and 35 to 50 minutes Or 40 minutes to 60 minutes. Specifically, it may be carried out at 25 to 35 DEG C for 40 to 50 minutes. By irradiating ultrasonic waves under the above conditions, the total energy consumption consumed in the production of graphene oxide can be minimized, and manufacturing cost can be reduced.

In addition, the step of irradiating ultrasonic waves may irradiate ultrasound at a frequency of 30 kHz to 60 kHz. Specifically, the step of irradiating ultrasonic waves may irradiate ultrasound at a frequency of 30 kHz to 55 kHz, 35 to 55 kHz, or 40 kHz to 50 kHz. More specifically, the step of irradiating ultrasonic waves may irradiate ultrasound at a frequency of 40 kHz to 50 kHz. By examining the frequency in the above range, the acid and the potassium permanganate can efficiently penetrate into the graphite in a short time, and the graphene oxide having excellent oxidation efficiency can be produced, and the manufacturing time and manufacturing cost can be reduced, and the fewer sheet grains Oxide and the size of the graphene oxide crystal can be uniform.

The acid used in the process for preparing graphene oxide according to the present invention may include two or more kinds selected from the group consisting of sulfuric acid, phosphoric acid, nitric acid and hydrochloric acid. Specifically, the acid may include sulfuric acid and phosphoric acid. As an example, the mixing ratio of sulfuric acid and phosphoric acid may comprise 8 to 13 volume parts of phosphoric acid based on 100 parts by volume of sulfuric acid. Specifically, the mixing ratio of sulfuric acid and phosphoric acid may include 9 to 12 volume parts of phosphoric acid based on 100 parts by volume of sulfuric acid. The use of the acid as described above has the advantage of being able to effectively penetrate the graphite and increase the oxidation efficiency.

In addition, in the process for producing graphene oxide according to the present invention, potassium permanganate may be added in an amount of 500 to 800 parts by weight based on 100 parts by weight of graphite. Specifically, the amount of potassium permanganate added may be 530 to 750 parts by weight, 550 to 700 parts by weight or 575 to 650 parts by weight based on 100 parts by weight of graphite. More specifically, the amount of potassium permanganate added may be 550 to 650 parts by weight based on 100 parts by weight of the graphite. By adding potassium permanganate at the above ratio, the oxidation efficiency of the graphite can be improved.

As an example, in the present invention, after the step of irradiating the mixture of graphite with acid and potassium permanganate with ultrasonic waves, the mixture may be a dark brown suspension.

In addition, the mixture having been subjected to the ultrasonic wave irradiation step may be cooled to room temperature (20 to 25 ° C), and the ice water, distilled water and / or hydrogen peroxide water may be slowly added. More specifically, the mixture may be cooled to room temperature and ice water and / or hydrogen peroxide water may be added to convert the residual permanganate to soluble manganese ions to remove the permanganate.

The method for producing graphene oxide according to the present invention may further comprise a step of washing the mixture of graphite with an acid and potassium permanganate after the step of irradiating ultrasonic waves. Specifically, in the washing step, the mixture subjected to the ultrasonic irradiation step may be filtered and washed with a diluted hydrochloric acid aqueous solution or water. More specifically, the step of washing can remove the metal ions by washing the mixture with a dilute aqueous hydrochloric acid solution.

As an example, the method of filtering the mixture through the ultrasonic wave irradiation step is not particularly limited as far as it is a method of separating a mixture of a solid and a liquid. For example, the method of filtration may include atmospheric filtration, pressure filtration or vacuum filtration.

In addition, the present invention may further include a step of drying after the washing. The drying step may be performed by drying the graphene oxide prepared at 20 ° C to 25 ° C for at least 24 hours. By drying under the above conditions, impurity-removed graphene oxide can be obtained.

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples.

However, the following Examples and Experimental Examples are merely illustrative of the present invention, and the present invention is not limited to the following Examples and Experimental Examples.

Example  One.

1 g of graphite and 6 g of KMnO ₄ were added to 120 ml of sulfuric acid (H ₂ SO ₄ ) and 13.3 ml of phosphoric acid (H ₃ PO ₄ ) and mixed for 1 minute to prepare a mixture. The prepared mixture was placed in a bath apparatus capable of being irradiated with ultrasonic waves and ultrasonically irradiated at 30 캜 for 45 minutes to obtain a dark brown suspension. The brown suspension was cooled to room temperature ice water and 133 ml of hydrogen peroxide (H ₂ O- ₂₎ of _30% was added slowly to a suspension of 1ml. At this time, the residual permanganate decreased to manganese ion, and the color of the suspension changed to yellowish brown. The light brown suspension was then filtered, washed with 250 ml of 10% hydrochloric acid (HCl) and dried in air for 24 hours to produce graphene oxide.

Comparative Example  One.

1 g of graphite, 6 g of potassium permanganate (KMnO ₄ ) and 1 g of sodium nitrate (NaNO ₃ ) were added to 120 ml of sulfuric acid (H ₂ SO ₄ ) and 13.3 ml of phosphoric acid (H ₃ PO ₄ ) And graphene oxide was prepared in the same manner as in Example 1, except that the process of irradiating ultrasonic waves was omitted, and heat was applied at 50 ° C. for 12 hours.

Comparative Example 2

Graphite was commercially obtained.

Experimental Example 1

The graphene oxide prepared in Example 1 and Comparative Example 1 and the graphite of Comparative Example 2 were injected to the graphene oxide prepared in Example 1 and Comparative Example 1 in order to confirm the form and content of graphene oxide produced by the process for producing graphene oxide according to the present invention Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), and High-resolution Transmission Electron Microscope (HRTEM) were performed. X-ray diffraction (XRD) and specific surface area of the graphene oxide prepared in Example 1 and Comparative Example 1 and the graphite of Comparative Example 2 were measured. The measured results were shown in FIGS. 1 and 2 2, Fig. 3 and Table 1.

2? (?) FWHM (°) Interlayer distance (nm) Crystalline diameter (nm) Floor number Specific surface area (m < 2 > / g) Example 1 9.68 2.52 0.968 3.23 4.33 112.0 Comparative Example 1 9.92 1.98 0.992 4.02 5.05 66.0 Comparative Example 2 26.52 0.12 0.335 69.3 207.86 60.0

Fig. 1 is an image of a graphene oxide of Example 1 and Comparative Example 1 and an image of a graphite of Comparative Example 2 taken by a scanning electron microscope, showing how graphitic particles of a carbon platelet-like crystalline form are laminated in graphite, And how the graphene sheet was peeled off from the graphene oxide of Comparative Example 1.

Referring to FIG. 1 (a), it can be seen that the graphite layers are stacked due to the van der Waals force in a graphite form of a laminated structure. Referring to FIG. 1 (b), it can be seen that the graphene oxide layer is effectively peeled off by ultrasonic irradiation at 45.degree. C. for 45 minutes under ultrasonic irradiation. 1 (c), it can be seen that the peeling does not proceed effectively as compared with Example 1, even though the substrate is heated to 50 ° C. for 12 hours. Therefore, it can be seen that the graphite having a laminated structure is effectively stripped by the thinner graphene oxide layer through the ultrasonic irradiation.

2 is an image of graphene oxide of Example 1 and Comparative Example 1 taken by a transmission electron microscope (TEM) and a high-resolution transmission electron microscope (HRTEM). 2 (a) is a transmission electron microscope image of graphene oxide of Example 1, and it is confirmed that the graphene oxide of Example 1 has a transparent thin sheet structure and few folds. FIG. 2 (b) is a transmission electron microscope image of the graphene oxide of Comparative Example 1, and the graphene oxide of Comparative Example 1 is thicker than the graphene oxide irradiated with ultrasonic waves and has many folded portions. 2 (c) is a high-resolution transmission electron microscope image of the graphene oxide of Example 1, and the graphene oxide of Example 1 is a honeycomb structure composed of a single layer and formed into small pores And the pore density is high. On the other hand, FIG. 2 (d) is a high-resolution transmission electron microscope image of graphene oxide of Comparative Example 1, which shows that the pore size is larger and the pore density is smaller than that of the graphene oxide of Example 1. This is because when the graphite is treated with an acid, the surface of the graphite is erosioned and a carboxyl group, a hydroxyl group, an epoxy and the like are formed in the carbon layer upon the oxidation of the graphite, thereby forming smaller pores. Therefore, it can be seen that the graphene oxide produced by ultrasonic irradiation is more efficiently peeled off by ultrasonic irradiation than the graphene oxide not subjected to ultrasonic irradiation.

3 is a X-ray diffraction measurement graph of graphite oxide of Example 1 and Comparative Example 1 and graphite of Comparative Example 2. Fig. Referring to FIG. 3, the graphite of Comparative Example 2 has a peak with a 2θ value of 26.52 ± 1.0 °, which indicates that the graphite of Comparative Example 2 has a layered structure. However, graphene oxide of Example 1 and Comparative Example 1 exhibited a (001) diffraction peak in which the (002) peak with a 2θ value of 26.52 ± 1.0 ° disappeared and broadened at 2θ values of 9.12 ± 1.0 ° and 8.9 ± 1.0 °, respectively . In the graphene oxide of Comparative Example 1, diffraction peaks of graphite (2 &thetas; = 31.19 DEG) were still observed, but in graphene oxide of Example 1, diffraction peaks of graphite were not observed. As a result, it can be seen that graphite was not sufficiently oxidized when heat was applied at 50 ° C for 12 hours without ultrasonic irradiation like the graphene oxide of Comparative Example 1.

Table 1 shows the diffraction angles (2?) Of the graphene oxide of Example 1 and Comparative Example 1 and the graphite of Comparative Example 2, the full width at half maximum of the main peak (FWHM), the interlayer distance (D) (N) of average sheets in the crystal. As shown in Table 1, the interlayer distance of the graphite of Comparative Example 2 is 0.335 nm, while the interlayer distances of the graphene oxide of Example 1 and Comparative Example 1 are 0.968 nm and 0.992 nm, respectively, -Bonded conjugated system is broken due to the insertion of an oxygen functional group such as a hydroxyl group, an epoxy group, a carbonyl group or a carboxyl group. The average crystallite diameter of the graphene oxide of Example 1 was about 3.23 nm, the number of sheets in the crystallite was about 4.33 and the graphene oxide of Comparative Example 1 was about 5.05 The graphene oxide according to the present invention contains fewer sheets. As a result, it can be seen that the method of producing graphene oxide according to the present invention includes a step of ultrasonic irradiation to produce a thinner sheet of graphene oxide having a higher rate of nucleation than crystal growth.

As can be seen from Table 1, the BET specific surface area of the graphene oxide of Example 1 is about 1.8 times higher than that of the graphene oxide of Comparative Example 1 and the graphite of Comparative Example 2.

Therefore, the graphene oxide prepared by the process for producing graphene oxide according to the present invention includes a step of irradiating ultrasound to oxidize graphene oxide sufficiently, resulting in peeling from a layer of graphite to form a thin layer, It can be seen that the specific surface area is wide.

Experimental Example  2.

X-ray photoelectron spectroscopy (X-ray photoelectron spectroscopy) was performed on graphite oxide prepared in Example 1 and Comparative Example 1 and graphite in Comparative Example 2 in order to confirm the binding properties between the components constituting the graphene oxide according to the present invention. ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) were measured. The measured results are shown in FIGS. 4 and 5.

Fig. 4 shows X-ray photoelectron spectroscopic results of graphite oxide of Example 1 and Comparative Example 1 and graphite of Comparative Example 2. Fig. Referring to FIG. 4, the graphene oxide of Example 1 has a higher binding energy of C1s than the graphene oxide of Comparative Example 1 and the graphite of Comparative Example 2. The graphene oxide of Example 1 is 0.914, the graphene oxide of Comparative Example 1 is 0.79, and the graphite of Comparative Example 2 is 0.12. This means that the binding energy between the carbon element and the oxygen element of the graphene oxide of Example 1 is increased.

C = C / C = C / CH at the bond energy of 284.5 ± 0.5 eV, 286.6 ± 0.5 eV and 287.6 ± 0.5 eV in the binding energy graph of C1s in the case of the graphene oxide of Example 1 and Comparative Example 1, The presence of peaks of CO and C = O can be confirmed. Furthermore, the graphene oxide of Example 1 has a strong peak bound to the oxygen element as compared with the graphene oxide of Comparative Example 1, and a peak of O-C = O exists at a binding energy of 289.1 ± 0.5 eV. This is because the graphene oxide of Example 1 contains more oxygen functional groups. 4, the four separated peaks can be observed, and quinone, C = 1, 2, 3, 4, 5 and 6 are observed at 530.3 ± 0.5 eV, 531.7 ± 0.5 eV, 532.5 ± 0.5 eV, and 535.3 ± 0.5 eV, O, CO and OH peaks are present. Further, it can be seen that the graphene oxide of Comparative Example 1 has a significantly weaker peak of oxygen functional group than the graphene oxide of Example 1. Thus, it can be seen that the method of producing graphene oxide according to the present invention efficiently oxidizes graphite by ultrasonic irradiation.

5 is a graph showing Fourier Transform-Infrared spectroscopy (FT-IR) measurement of graphene oxide of Example 1 and Comparative Example 1 and graphite of Comparative Example 2. Fig. Referring to FIG. 5, the graphite of Comparative Example 2 can confirm that the OH bond exists through the peak located in the region of 3627 ± 5 cm ^-1 , and the CO bond exists through the peak located in the region of 1031 ± 5 cm ^-1 . The graphene oxide of Example 1 and Comparative Example 1 also had OH bonds through peaks located in the region of 3000 to 3600 cm ^-1 , C═O bonds through peaks located in the region of 1728 ± 5 cm ^-1 , 1615 ± 5, a C = C bond with a peak area located in cm ^-1, 1627 ± 5 of HOH bond with a peak area located in cm ^-1, 1274 ± 5 cm ^-1 region of CO epoxy bonded via a peak located at, 1627 The CO carboxyl bond can be confirmed in the region of ± 5 cm ^-1 . As described above, the existence of a carboxyl group and an epoxy group indicates that the graphite is oxidized, and an oxygen functional group is added to the carbon element to break the π conjugated orbitals of the graphite. However, the graphene oxide of Comparative Example 1 has a weaker intensity of the oxygen functional group and hydroxyl group absorption spectrum than the graphene oxide of Example 1. This is because the graphene oxide of Example 1 was oxidized more easily by irradiating ultrasonic waves in the graphite oxidation process. Therefore, the method of preparing graphene oxide according to the present invention does not require high temperature, pressure, and cooling time because the oxidation reaction is actively performed by providing more active sites between carbon layers through ultrasonic irradiation.

Experimental Example  3.

In order to confirm the optical properties of the graphene oxide according to the present invention, the graphene oxide of Example 1 and Comparative Example 1 and the graphite of Comparative Example 2 were subjected to UV-1601PC UV-Vis spectroscopy of Shimadzu, Japan The UV-visible absorbance was measured using a UV-Vis spectrophotometer and is shown in FIG.

6, all the graphs of Example 1, Comparative Example 1, and Comparative Example 2 show that there is an absorbance peak due to? -Π ^* transition in the region of 200 to 300 nm. Specifically, the graphite of Comparative Example 2 shows a weak peak at about 250 nm, and the graphene oxide of Comparative Example 1 shows a weak and broad peak at 233 nm. On the other hand, the graphene oxide of Example 1 exhibits a strong peak at 227 nm, and the peak of C = O absorbance due to η-π ^* transition is weakly present in the region of 300 nm. The graphene oxide of Example 1 is observed at a shorter wavelength of absorption peak due to the transfer of π-π ^* than that of the graphene oxide of Comparative Example 1, which means that the oxidation of graphene oxide of Example 1 is more advanced to be.

Experimental Example  4.

The graphene oxide of Example 1 and Comparative Example 1 and the Raman spectrum of the graphite of Comparative Example 2 were measured and the results are shown in FIG. 7 (a) shows Raman spectrum of graphite of Comparative Example 2, (b) shows Raman spectrum of graphene oxide of Example 1, and (c) shows Raman spectrum of graphene oxide of Comparative Example 1 (D) shows the 2D Raman spectrum of the graphene oxide of Example 1 and Comparative Example 1, respectively.

7, it can be seen that the graphene oxide of Example 1 and Comparative Example 1 is broader in D peak and stronger in strength than the graphite of Comparative Example 2. Specifically, the graphite of Comparative Example 2 has a G band in the region of 1580 ± 5 cm ^-1 , a D peak in the region of 1350 ± 5 cm ^-1 , and the shape of the peak is sharp. On the other hand, in the graphene oxide of Example 1 and Comparative Example 1, the G band was observed in the regions of 1595 ± 2 cm ^-1 and 1592 ± 2 cm ^-1 , and 1361 ± 5 cm ^-1 and 1351 ± 5 cm ^-1 regions D peak is observed and the shape of the peak is broad. At this time, the G band shifts to a higher energy band as the layer becomes thinner, and the D peak within graphene oxide has a substituent such as a hydroxyl group and / or an epoxy group on the carbon surface, (broad) appears. In addition, the I _D / I _G intensity ratio used as a disorder index of graphene is about 0.97 in the graphene oxide of Example 1, which is 0.95 which is the value of the graphene oxide of Comparative Example 1 and 0.7 of the graphite of Comparative Example 2 Higher. As a result, it can be seen that graphene oxide has a higher carbon content than that of graphite due to substitution of oxygen functional groups.

7 (d), a 2D peak is observed at about 2700 cm ^-1 , and the graphene oxide of Example 1 is broader than the graphene oxide of Comparative Example 1 and has an upshifted peak . It can be seen that the graphene oxide of Example 1 is composed of a thinner layer than that of the graphene oxide of Comparative Example 1.

Experimental Example 5

Thermogravimetric analysis of graphene oxide of Example 1 and Comparative Example 1 and graphite of Comparative Example 2 was performed to evaluate the degree of loss of graphene oxide according to the present invention. At this time, the thermogravimetric analysis was performed by raising the temperature from 0 ° C to 800 ° C at a rate of 10 ° C / min under a nitrogen gas atmosphere using a thermogravimetric analyzer, and the results are shown in FIG.

8, graphite of Comparative Example 2 showed a weight loss of about 13.39% due to a decrease in weight in a range of about 650 ° C or higher, and the graphene oxide of Example 1 and Comparative Example 1 had a weight Reduction occurs. Specifically, in the range of 50 to 170 캜, the graphene oxide of Example 1 shows a weight loss of about 36.74% and the graphene oxide of Comparative Example 1 shows a weight loss of 26.42%. This is because water molecules present between graphene oxide are removed. It can also be seen that the weight loss of graphene oxide of Example 1 is about 15.42% and the weight loss of graphene oxide of Comparative Example 1 is about 26.9% at 170 to 380 ° C. It can be seen that the graphene oxide of Example 1 is stable to heat and is reduced at a smaller rate than the graphene oxide of Comparative Example 1 due to the process in which the hydroxyl group, the epoxy group and the remaining water molecules are removed. In addition, carbon monoxide and carbon dioxide were generated by pyrolysis of the carbon and oxygen functional groups remaining in graphene oxide in the range of 380 ° C or higher, and finally, when thermally decomposed at 800 ° C, the graphene oxides of Example 1 and Comparative Example 1 were about 86.14% Indicating a weight loss of about 82.12%.

Experimental Example  6.

In order to investigate the energy consumption efficiency of the process for producing graphene oxide according to the present invention, in the process for producing graphene oxide of Example 1 and Comparative Example 1, the yield of graphene oxide obtained through 1 g of graphite, , Time energy consumption, heat and time energy consumption, and manufacturing cost per gram were measured, and the results are shown in Table 2 below.

Example 1 Comparative Example 1 Synthesis condition 30 ° C, 45 minutes
(Ultrasonic irradiation) 50 캜, 12 hours
(Ultrasonic irradiation) Yield (g) 1.69 1.35 Total energy consumption
(heat, kW · h / g) 0.026
(96.67 kJ) 0.116
(421.11 kJ) Total energy consumption
(time, kW · h / g) 0.1170 2.160 Total energy consumption
(heat + time, kW · h / g) 0.143 2.276 Gross cost / g ($ / g) 0.02 0.32

Referring to Table 2, the graphene oxide of Example 1 was prepared by irradiating ultrasonic waves at 30 ° C for 45 minutes, and the graphene oxide of Comparative Example 1 was prepared by heating at 50 ° C for 12 hours. The graphene oxide of Example 1 The oxide yield was 1.69 g, which is larger than the 1.35 g gain of the graphene oxide of Comparative Example 1 by about 1.25 times. As in Example 1, the total energy consumption for raising the temperature from room temperature (20 ° C) to 30 ° C was 0.026 kWh / g, and the temperature was increased from room temperature (20 ° C) to 50 ° C Total energy consumption is 0.116 kW · h / g. In addition, the total energy consumption for producing graphene oxide for 45 minutes as in Example 1 was 0.117 kWh / g, and the total energy consumption for producing graphene oxide for 12 hours as in Comparative Example 1 was 2.160 kW · H / g. Thus, the total amount of energy consumed in maintaining the production time and temperature was 0.143 kWh / g in Example 1 and 2.276 kWh / g in Comparative Example 1, It can be seen that the manufacturing method is efficient in terms of the energy consumption rate. In addition, from the viewpoint of the manufacturing cost per 1 g, the cost of Example 1 is about 0.02 dollars per gram, while that of Comparative Example 1 is about 0.32 dollars per gram. Therefore, it can be seen that the method of producing graphene oxide according to the present invention is advantageous not only in terms of energy consumption but also in manufacturing cost.

Claims (6)

Comprising the step of irradiating a mixture of graphite with an acid and potassium permanganate with ultrasonic waves,
Wherein the step of irradiating the ultrasonic waves is performed at 20 to 50 DEG C for 30 to 70 minutes.
The method according to claim 1,
Wherein the acid comprises at least two selected from the group consisting of sulfuric acid, phosphoric acid, nitric acid, and hydrochloric acid.
The method according to claim 1,
Wherein the potassium permanganate is added in an amount of 500 to 800 parts by weight based on 100 parts by weight of the graphite in the step of irradiating ultrasonic waves.
The method according to claim 1,
Wherein the step of irradiating ultrasonic waves comprises irradiating ultrasound at a frequency of 30 kHz to 60 kHz.
The method according to claim 1,
And washing the ultrasonic wave after the step of irradiating the ultrasonic wave. 6. The method of claim 5,
Further comprising the step of drying after the step of washing.

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