KR102594796B1 - Method for preparing crystalline graphene oxide - Google Patents

Abstract

The present invention relates to a method for producing crystalline graphene oxide, and more specifically, to produce a powder-type carbon structure by hydrothermal synthesis of carbon raw materials, and to produce a powder-type carbon structure by applying photoheat induced by photoreaction to the powder-type carbon structure. It relates to a method of manufacturing crystalline graphene oxide using the photothermal effect.

Description

Method for preparing crystalline graphene oxide {Method for preparing crystalline graphene oxide}

The present invention relates to a method for producing crystalline graphene oxide, and more specifically, to produce a powder-type carbon structure by hydrothermal synthesis of carbon raw materials, and to produce a powder-type carbon structure and photoheat induced by photoreaction in the powder-type carbon structure. To provide a method of manufacturing crystalline graphene oxide using the photothermal effect.

Graphene refers to a two-dimensional thin film with a honeycomb structure composed of one or multiple layers of carbon (C) atoms. Since Russian physicists Andre Geim and Professor Konstantin Novoselov separated graphene from graphite through mechanical exfoliation in 2004, research on graphene has been continuously reported. Graphene, which has this unique structure, has a high electron mobility of about 20,000 to 50,000 cm ² /Vs, a thermal conductivity of 5,300 W/mK, which is more than twice that of diamond, which has a high thermal conductivity, a very large specific surface area compared to volume, and physical and chemical properties. It is known to have stability, and its application potential is emerging in the fields of transparent electrodes, next-generation semiconductors, energy storage and conversion devices, functional composite materials, barrier coatings, and heat dissipation materials.

In the early stages of graphene development, a top-down mechanical peeling method was used to attach a pencil lead to Scotch tape and then repeatedly peel and attach it, followed by a chemical vapor deposition method that can produce one-layer and several-layer thin films of highly crystalline graphene. ), epitaxial growth, etc., are being studied in a variety of bottom-up approach manufacturing techniques, and research and development on large-area, mass production for commercial use is continuously being conducted.

Chemical exfoliation and chemical vapor deposition methods are applied as synthesis methods for large-area, mass production of graphene for commercial use. In the case of chemical exfoliation, it is known as the synthesis method that comes closest to the two goals of large-area production and mass production of graphene, and graphene can be produced through oxidation-reduction of bulk simple materials such as graphite. Although it has high physical properties and is easy to apply to application fields, it has the disadvantage of being difficult to completely remove defects in the final graphene result due to the oxidation-reduction process and various acids, functional groups, and impurities bonded to carbon atoms. In the case of chemical vapor deposition, it is possible to produce one or several layers of graphene sheets with high crystallinity, and by applying a roll-to-roll process, it is possible to produce a flexible graphene-based film. It has the disadvantage of requiring high temperatures and a synthesis chamber when synthesizing pins, and since large-area production is possible only in film form, its application areas are limited.

Recently, among the bottom-up synthesis methods, the hydrothermal synthesis method is receiving a lot of attention in the production of crystalline graphene as it allows for large-area and mass production. However, most of the carbon-based low-molecular-weight materials used in this process are acidic, and when synthesized at low temperatures, the crystals and quality of the synthesized carbon matrix are weak, which limits their application in research and has the disadvantage of requiring an additional purification process. Therefore, an increase in process time and manufacturing cost is inevitable.

Therefore, in order to supplement the problems that need to be solved for the commercial use of graphene, the present inventors developed a method for producing crystalline graphene oxide that has a simple manufacturing process and is easy to apply to mass industry and is free from impurities. Recognizing that it was urgent, the present invention was completed.

Republic of Korea Patent Publication No. 10-2129553

The purpose of the present invention is to manufacture a powder-type carbon structure by hydrothermal synthesis of carbon raw materials, and to produce crystalline graphene oxide by using the photothermal effect induced by photoreaction on the powder-type carbon structure. To provide a manufacturing method.

The technical problems to be achieved by the invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by those skilled in the art from the description of the present invention.

In order to achieve the above object, the present invention provides a method for producing crystalline graphene oxide.

Hereinafter, this specification will be described in more detail.

The present invention provides a method for producing crystalline graphene oxide, comprising the following steps.

(S1) manufacturing a powder-type carbon structure through hydrothermal synthesis;

(S2) dispersing the powdered carbon structure in a solvent;

(S3) Manufacturing crystalline graphene oxide by irradiating light to the dispersed carbon structure.

In the present invention, the step (S1) is characterized by consisting of the following steps.

(S1A) preparing a mixture by mixing carbon raw materials and solvents;

(S1B) adding a pH adjuster to the mixture; and

(S1C) Step of producing a powder-type carbon structure by hydrothermal synthesis of the mixture to which the pH adjuster is added.

In the present invention, the carbon raw material in the (S1A) step is a compound containing carbon, such as acetic acid, acetone, benzene, benzyl alcohol, butanol, and butane. Butanone, chlorobenzene, chloroform, citric acid, ethanol, ethyl acetate, ethylene glycol, gallic acid, glucose ), hexane, pyrogallol, tannic acid, and xylene.

In the present invention, the solvent in the step (S1A) is water, hexane, benzene, toluene, xylene, chlorobenzoic acid, hexadecence, At least one selected from the group consisting of tetradecence, octadecene, methanol, ethanol, propanol, butanol, hexanol, and acetone. It is characterized by

In the present invention, the pH adjuster in the (S1B) step is at least one selected from the group consisting of sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonia water (NH ₄ OH), and calcium hydroxide (Ca(OH) ₂ ). It is characterized by

In the present invention, the hydrothermal synthesis is performed at 100 to 300 ° C. for 1 to 5 hours.

In the present invention, the step (S3) is performed by adding a pulse width of 0.1 to 5 ms, a pulse repetition rate of 0.1 to 5 Hz, and a pulse number of 10 to 100 to the dispersed carbon structure. number) and a total energy density of 1 to 400 J/cm ² to produce crystalline graphene oxide.

The method for producing crystalline graphene oxide of the present invention does not require any separate materials for producing graphene by directly using carbon raw materials, and produces graphene oxide with high crystallinity according to photoreaction conditions. This makes it easy to apply to various industrial fields.

In addition, the method for producing crystalline graphene oxide of the present invention has normal hydrothermal synthesis and photoreaction conditions compared to conventional conditions, making it easy to apply to mass industrial fields.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

Figure 1 is a block diagram schematically showing a method for producing crystalline graphene oxide according to the present invention.
Figure 2 is a transmission electron microscope (TEM) image of (a) a powdery carbon structure (Example 1.1.) and (b) crystalline graphene oxide (Example 1.2.) prepared according to the present invention.
Figure 3 is an This is a pattern confirmed through .
Figure 4 is a Raman spectrum of powdered graphene oxide (Example 1.1, blue line) and crystalline graphene oxide (Example 1.2, greeb line) prepared according to the present invention.

The terms used in this specification are general terms that are currently widely used as much as possible while considering the function in the present invention, but this may vary depending on the intention or precedent of a person working in the art, the emergence of new technology, etc. In addition, in certain cases, there are terms arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the description of the relevant invention. Therefore, the terms used in the present invention should be defined based on the meaning of the term and the overall content of the present invention, rather than simply the name of the term.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless clearly defined in the present application, should not be interpreted in an ideal or excessively formal sense. No.

The numerical range includes the values defined in the range above. Every maximum numerical limit given throughout this specification includes all lower numerical limits as if the lower numerical limit were explicitly written out. Every minimum numerical limit given throughout this specification includes every higher numerical limit as if such higher numerical limit was clearly written. All numerical limits given throughout this specification will include all better numerical ranges within the broader numerical range, as if the narrower numerical limits were clearly written.

Hereinafter, examples of the present invention will be described in detail, but it is obvious that the present invention is not limited to the following examples.

Crystalline graphene oxide manufacturing method

The present invention provides a method for producing crystalline graphene oxide comprising the following steps.

(S1) manufacturing a powder-type carbon structure through hydrothermal synthesis;

(S2) dispersing the powder-type carbon structure in a solvent;

(S3) manufacturing crystalline graphene oxide by irradiating light to the dispersed carbon structure;

The step (S1) is a step of manufacturing a carbon structure in powder form and may consist of the following steps.

(S1A) preparing a mixture by mixing carbon raw materials and solvents;

(S1B) adding a pH adjuster to the mixture; and

(S1C) Step of producing a powder-type carbon structure by hydrothermal synthesis of the mixture to which the pH adjuster is added.

More specifically, in the step (S1A), the carbon raw material is a compound containing carbon, acetic acid, acetone, benzene, benzyl alcohol, butanol, and butanone. (butanone), chlorobenzene, chloroform, citric acid, ethanol, ethyl acetate, ethylene glycol, gallic acid, glucose , hexane, pyrogallol, tannic acid, and xylene.

The solvent in the step (S1A) is water, hexane, benzene, toluene, xylene, chlorobenzoic acid, hexadecence, and tetradecence. , octadecene, methanol, ethanol, propanol, butanol, hexanol, and acetone, and may be one or more selected from the group consisting of, and are preferred. It may be one or more selected from the group consisting of water, methanol, ethanol, propanol, butanol, hexane, benzene, toluene, and xylene.

The pH adjuster in the step (S1B) is a base of pH 8 or higher, preferably 1 selected from the group consisting of sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonia water (NH ₄ OH), and calcium hydroxide (Ca(OH) ₂ ). There may be more than one species.

The hydrothermal synthesis can be performed at a temperature range of 100 to 300°C for 1 to 5 hours, and preferably at a temperature range of 200 to 250°C for 2 to 3 hours. If the temperature range of the hydrothermal synthesis is less than 100°C, there may be a problem in that the core of graphene oxide is not created or amorphous carbon is formed. Additionally, if the reaction time is less than 1 hour, there may be a problem in which thermal decomposition of the carbon raw material is not sufficiently achieved, and if the reaction time exceeds 5 hours, there may be a problem due to agglomeration of the synthesized graphene oxide.

The powdery carbon structure prepared in the step (S1C) may additionally include washing and drying with an organic solvent to remove impurities present on the powdery carbon structure. More specifically, the powdered carbon structure prepared through hydrothermal synthesis in the step (S1C) is added to an organic solvent, separated using centrifugation, and dried in a vacuum at 50 to 70 ° C. for 1 to 24 hours. A powder-type carbon structure from which impurities have been removed can be manufactured.

The organic solvent is C _1-4 alcohol, 1,4-dioxane, acetone, ethyl acetate, toluene, acetonitrile, and tetrahydrofuran. It may be one or more types selected from the group consisting of (tetrahydrofuran), and preferably may be one or more types selected from the group consisting of methanol, ethanol, acetone, ethyl acetate, and acetonitrile.

The carbon structure prepared in step (S1) is in the form of a non-crystalline powder and may exist in an agglomerated state.

The (S2) step is a step of dispersing the powdery carbon structure prepared in the (S1) step in a dispersion solvent. More specifically, the powdery graphene oxide is dispersed in water (H ₂ O) as a dispersion solvent. It can be dispersed.

The powdered carbon structure can be mixed and dispersed in a dispersion solvent at a ratio of 0.1 wt% to 1 wt% (powdered graphene oxide: dispersion solvent). After mixing the powdered carbon structure and the dispersion solvent, a homogeneous It can be mixed using a machine at a speed of 5,000 to 20,000 rpm for 0.1 to 6 hours.

The step (S3) is a step of manufacturing crystalline graphene oxide. More specifically, the dispersed carbon structure is provided with a pulse width of 0.1 to 5 ms and a pulse repetition rate of 0.1 to 5 Hz. , crystalline graphene oxide can be produced by irradiating light with a pulse number of 10 to 100 and a total energy density of 1 to 400 J/cm ² .

When light in a range exceeding the pulse width, pulse repetition rate, pulse number, and energy density is irradiated, the manufactured crystalline graphene oxide may be damaged and crystallinity may be impaired.

Since the step (S3) is performed in a solvent, the solvent absorbs heat generated upon light irradiation, thereby preventing excessive structural changes in the crystalline graphene oxide due to the heat. In addition, when using an organic solvent, the heat generated during light irradiation induces thermal decomposition of the organic solvent, and the thermal decomposition product can be used as a carbon source when recovering the crystal structure of the carbon structure.

The light in step (S3) may be irradiated using a xenon flash lamp with a wavelength of 300 to 1,000 nm.

The advantages and features of the present invention and methods for achieving them will become clear with reference to the embodiments described in detail below. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms, and only the embodiments are provided to ensure that the disclosure of the present invention is complete, and are provided by those skilled in the art It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims.

Example 1. Production of crystalline graphene

1.1. Powder-type carbon structure manufacturing

Carbon raw materials citric acid, tannic acid, and ethanol were mixed, and sodium hydroxide (NaOH) was added to the mixture as a pH adjuster. The pH-adjusted mixture was subjected to hydrothermal synthesis to prepare a powder-type carbon structure, which was washed repeatedly with ethanol by centrifugation 5 times at 10,000 rpm for 10 minutes, filtered using a vacuum filtration device, and then vacuum-filtered at 70°C. A powder-type carbon structure from which impurities were removed was prepared by drying in an oven for 10 hours.

1.2. Crystalline graphene oxide manufacturing

The prepared powdered graphene oxide was dispersed in water at a concentration of 5 g/L and dispersed at 10,000 rpm for 30 minutes using a homogenizer. The dispersion was processed using a xenon flash lamp with multicolor light (wavelength range of 300 nm to 800 nm) at a pulse width of 1 ms, a pulse repetition rate of 2 Hz, and a pulse number of 50. ) and 200 J/cm ² of total energy density (total energy density) were irradiated to produce crystalline graphene oxide.

Experimental Example 1. Confirmation of crystal morphology

In order to confirm the crystal morphology of the crystalline graphene oxide prepared in Example 1, the powder-type carbon structure (Example 1.1.) and the crystalline graphene oxide (Example 1.2.) were examined under a transmission electron microscope (Example 1.2). The morphology was confirmed through a transmission electron microscope (TEM), and is shown in Figure 2.

The powder-type carbon structure (Example 1.1.) is a mixture of amorphous carbon structure and nano-sized graphene structure, and it can be confirmed that the small molecules decomposed from the carbon raw material that were not completely removed after the reaction are in an agglomerated state because they surround the carbon structure. . On the other hand, it can be seen that crystalline graphene oxide (Example 1.2.) clearly shows the crystalline characteristics of graphene.

Experimental Example 2. Confirmation of crystalline

In order to confirm the crystallinity of the crystalline graphene oxide prepared in Example 1, the powder-type carbon structure (Example 1.1., black line) and the crystalline graphene oxide (Example 1.2., red line) were Crystallinity was confirmed through X-ray diffraction analysis (XRD), and this is shown in Figure 3.

Referring to Figure 3, the XRD pattern of the powdered carbon structure (Example 1.1, blue line) shows a broad pattern corresponding to the (002) plane of graphite at 21°, and 29°, 31°, and 33°. Patterns such as ° were additionally observed. The above peak is a residual pattern of citric acid that has not been completely thermally decomposed and does not correspond to a graphite structure. On the other hand, crystalline graphene oxide (Example 1.2., green line) has a pulse width of 21 under the conditions of a pulse width of 1 ms, a pulse repetition rate of 2 Hz, and a pulse number of 50. It can be seen that only a broad peak corresponding to the (002) plane of graphite is formed at °. This can be said to be due to processing of the photothermal effect induced by the light reaction.

Experimental Example 3. Confirmation of crystal atomic arrangement

In order to confirm the crystal atomic arrangement of the crystalline graphene oxide prepared in Example 1, a powder-type carbon structure (Example 1.1., blue line) and crystalline graphene oxide (Example 1.2., green line) were used. The Raman spectrum was measured and is shown in Figure 4.

Referring to Figure 4, the G mode in the Raman spectrum is related to the in-plane vibration mode containing sp ² carbon atoms, and the D mode is caused by structural defects and disordered states such as oxygen functional groups, so the D and G bands of The intensity ratio can be used to determine the level of disorder in carbon materials. In the powdered carbon structure (Example 1.1.), the D and G modes commonly found in carbon-based materials are found, and the vibration mode appearing in tannic acid is observed at the same time, which can be seen as tannic acid that has not been completely thermally decomposed. . On the other hand, crystalline graphene oxide (Example 1.2.) clearly shows D mode and G mode, and the value of I _D /I _G was confirmed to be 0.71. The crystalline graphene oxide has a relatively high I _D /I _G value compared to pure graphene, which can be said to be observed due to the oxygen functional group.

From the above description, those skilled in the art to which the present invention pertains will understand that the present invention can be implemented in other specific forms without changing its technical idea or essential features. In this regard, the embodiments described above should be understood in all respects as illustrative and not restrictive.

Claims (5)

(S1) manufacturing a powder-type carbon structure through hydrothermal synthesis;
(S2) dispersing the powder-type carbon structure in a solvent; and
(S3) manufacturing crystalline graphene oxide by irradiating the dispersed carbon structure with light,
The hydrothermal synthesis is performed for 1 to 5 hours at a temperature range of 100 to 300°C,
The light irradiation has a pulse width of 0.1 to 5 ms, a pulse repetition rate of 0.1 to 5 Hz, a pulse number of 10 to 100, and a total energy of 1 to 400 J/cm ² A method for producing crystalline graphene oxide, which involves irradiating light with a total energy density. According to paragraph 1,
The (S1) step is
(S1A) preparing a mixture by mixing carbon raw materials and solvents;
(S1B) adding a pH adjuster to the mixture; and
(S1C) producing a powder-type carbon structure by hydrothermal synthesis of the mixture to which the pH adjuster has been added. According to paragraph 2,
The carbon raw materials in the (S1A) step are acetic acid, acetone, benzene, benzyl alcohol, butanol, butanone, chlorobenzene, and chloroform. (chloroform), citric acid, ethanol, ethyl acetate, ethylene glycol, gallic acid, glucose, hexane, Pyrogallol , one or more selected from the group consisting of tannic acid and xylene,
The solvent in the step (S1A) is water, hexane, benzene, toluene, xylene, chlorobenzoic acid, hexadecence, and tetradecence. , octadecene, methanol, ethanol, propanol, butanol, hexanol, and acetone, at least one selected from the group consisting of,
The pH adjuster in the (S1B) step is a crystalline product, characterized in that at least one selected from the group consisting of sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonia water (NH ₄ OH), and calcium hydroxide (Ca(OH) ₂ ). Method for producing graphene oxide. delete delete