WO2019198985A2 - Method for producing graphene oxide - Google Patents

Method for producing graphene oxide Download PDF

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WO2019198985A2
WO2019198985A2 PCT/KR2019/004056 KR2019004056W WO2019198985A2 WO 2019198985 A2 WO2019198985 A2 WO 2019198985A2 KR 2019004056 W KR2019004056 W KR 2019004056W WO 2019198985 A2 WO2019198985 A2 WO 2019198985A2
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graphene oxide
present
heat treatment
manufacturing
prepared
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PCT/KR2019/004056
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French (fr)
Korean (ko)
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WO2019198985A3 (en
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이선숙
안기석
임종선
명성
송우석
윤여흥
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한국화학연구원
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/198—Graphene oxide
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/20—Graphite
    • C01B32/21—After-treatment
    • C01B32/23—Oxidation
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/52—Electrically conductive inks

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  • the present invention relates to a graphene oxide production method for producing graphene oxide using a metal carbonate.
  • Graphene refers to a new material having a honeycomb structure in which carbon atoms are sp 2 bonds. Such graphene has the advantages of transparency, electrical conductivity, thermal conductivity, and mechanical strength in comparison with thickness, and also has a wide surface area. According to these advantages, graphene is used in various advanced fields such as advanced electronic devices, sensors, supercapacitors, and solar cells, and related research is being actively conducted.
  • Such graphene production methods include mechanical peeling, chemical vapor deposition, epitaxial growth, and chemical reduction.
  • a relatively low mass production method is possible by chemical reduction.
  • the chemical reduction method produces graphene oxide by oxidizing graphite, and then reduces the graphene oxide, thereby producing reduced graphene oxide (RGO). have.
  • the Hummer method (Hummer's method) or the Brodie method (Brodie's method) may be used to prepare graphene oxide.
  • an improved Hummer method (Modified Hummer's method), which is an improvement of the Hummer method.
  • the prior art (CARBON 2013, 64, pp. 225 ⁇ 229) is to provide an improved improved Hummer method, but there is still a problem causing environmental problems using concentrated sulfuric acid.
  • Another object of the present invention is to provide a graphene oxide production method that can economically produce graphene oxide in a short time.
  • Still another object of the present invention is to provide a method for producing graphene oxide, in which impurities are easily washed to simplify the cleaning process and hardly contain impurities.
  • Still another object of the present invention is to provide a method for producing graphene oxide, which minimizes the discharge of liquid waste in a dry process.
  • Still another object of the present invention is to provide a graphene oxide manufacturing method capable of producing a single layer of graphene oxide.
  • the method for producing graphene oxide according to the present invention includes a step of heat treatment by mixing graphite and metal carbonate.
  • the heat treatment may be performed by a dry process.
  • the heat treatment step of the heat treatment may be performed at 500 to 1200 °C.
  • the weight ratio of graphite: metal carbonate mixed in the heat treatment step may be 1: 1 to 10.
  • the metal included in the metal carbonate may be a Group 1 metal.
  • the heat treatment step may be performed for 10 minutes or more.
  • the primary oxide produced after the heat treatment step may further comprise a washing step of washing with 0.5 to 5% by weight inorganic acid aqueous solution.
  • the present invention also provides graphene oxide, the graphene oxide according to the present invention may be prepared by the graphene oxide production method according to an embodiment of the present invention.
  • Graphene oxide according to an embodiment of the present invention may be a carbon / oxygen atom ratio contained in the graphene oxide is 1.75 or more.
  • the zeta potential of the graphene oxide based on 1 mg of graphene oxide dispersed in 1 ml of water may be -20 to -50 mV.
  • the present invention also provides a method for producing reduced graphene oxide, the method for producing reduced graphene oxide according to the present invention includes the step of reducing the graphene oxide prepared by the method for producing graphene oxide according to an embodiment of the present invention. It may be prepared by.
  • the present invention has the advantage that the graphene oxide can be produced in a short time without using a high concentration of acidic solution by heat-treating the graphite and metal carbonate in a dry process.
  • the product included in the oxide produced primarily includes metal ions, so that impurities can be easily cleaned.
  • Figure 1 shows the analysis of the surface of the graphene oxide prepared by the embodiment of the present invention.
  • FIG. 2 illustrates X-ray photoelectron spectroscopy (XPS) analysis of graphene oxide according to examples and comparative examples of the present invention.
  • Figure 3 shows the Raman spectrum of the graphene oxide according to the Examples and Comparative Examples of the present invention.
  • XRD 4 shows X-ray diffraction spectra (XRD) of graphene oxide according to examples and comparative examples of the present invention.
  • Figure 5 shows the thermal stability of the graphene oxide according to the Examples and Comparative Examples of the present invention.
  • FIG. 6 is a graph illustrating the FT-IR of graphene oxide according to Examples and Comparative Examples of the present invention.
  • FIG. 7 shows examples of the present invention, a comparative example, and a measurement of contact angle, reflectance, and absorbance of reduced graphene prepared by reducing them through heat treatment, respectively.
  • Units of% and ratio used without particular mention in the present invention mean weight% and weight ratio, and unless otherwise defined, means weight% of any one of the total compositions in the composition.
  • the method for producing graphene oxide according to the present invention includes a step of heat treatment by mixing graphite and metal carbonate.
  • the present invention provides a method for producing graphene oxide, and the method for producing graphene oxide according to the present invention includes a step of mixing and heat treating graphite and metal carbonate.
  • the graphene oxide production method according to the present invention is capable of producing graphene oxide in a short time without using a strong acid such as sulfuric acid, nitric acid or phosphoric acid, and has the advantage of easy removal of impurities.
  • Hummer's method which is widely known in the art, is difficult to treat concentrated sulfuric acid discharged to waste liquid by performing an oxidation reaction on a solvent such as concentrated sulfuric acid, and there is a problem of causing environmental problems in the process of diluting it.
  • Hummer's method which is commonly used, requires a long reaction time of at least 2 hours, typically 8 hours or more, and thus requires a long time for synthesizing graphene oxide.
  • sulfur may be included in the graphene oxide as impurities about 0.05 to 0.5%.
  • the graphene oxide manufacturing method according to the present invention does not require a strong acid does not cause the problem of the treatment of waste liquid, it is possible to reduce the waste liquid treatment costs additionally generated during the production of graphene oxide.
  • it is possible to produce graphene oxide even by a heat treatment for a short time there is an advantage that can produce a large amount of graphene oxide in a short time.
  • the method for producing graphene oxide according to the present invention is an impurity included after the heat treatment of the graphite is a metal oxide, relatively easy to clean, there is an advantage that can produce a high purity graphene even by eliminating some of the cleaning process.
  • the heat treatment may be performed by a dry process.
  • Graphene oxide manufacturing method according to an embodiment of the present invention by performing the oxidation reaction in a dry process without the above-mentioned strong acid solvent has the advantage of preventing the environmental pollution problem by strong acid, and minimize the waste fluid.
  • the Hummer's method has been used in the manufacture of graphene oxide in the prior art because it has the advantage of producing graphene oxide in a single layer despite environmental problems using a strong acid.
  • the graphene oxide manufacturing method according to the present invention has a merit that a single layer of graphene oxide can be produced without the discharge of strong acid wastewater by a dry process, and the ratio of the reduced graphene oxide which is subsequently produced by such a single layer of graphene oxide There is an advantage that can significantly improve characteristics such as surface area and electrical conductivity.
  • the heat treatment of the heat treatment step in the graphene oxide manufacturing method according to an embodiment of the present invention may be 500 to 1200 °C, specifically 600 to 1000 °C, more specifically 700 to 900 °C. While improving the synthesis efficiency of graphene oxide in the above-described temperature range, there is an advantage that can be prevented from lowering the production efficiency of graphene oxide due to excessively high temperature.
  • Atmosphere in the heat treatment step may be used without limitation as long as the atmosphere containing oxygen, it may be air as one non-limiting example.
  • the weight ratio of graphite to the metal carbonate mixed in the heat treatment step is 1: 1 to 10, specifically 1: 1 to 6, more specifically 1: 1 To 4 may be. While increasing the production yield of graphene oxide in the above-described range, it is possible to prevent the problem that impurities are contained in the graphene oxide to be produced later with excessive metal carbonate content.
  • the metal included in the metal carbonate may be a Group 1 metal, specifically, one or two or more selected from lithium, sodium, and potassium, and more specifically, the metal carbonate may be Li 2 CO 3 , Na 2 CO 3, and K. It may include one or two or more selected from 2 CO 3 and the like, but this is only an example of the Group 1 metal carbonate, the present invention is not limited thereto.
  • the heat treatment step may be carried out without limitation during the time to produce the graphene oxide by the oxidation reaction of the graphite, for example may be performed for 10 minutes or more. Preferably 10 to 120 minutes, more preferably 20 to 80 minutes can be carried out but this is a preferred example and not limited thereto.
  • Graphene oxide manufacturing method according to an embodiment of the present invention unlike the conventionally known graphene oxide manufacturing method, it is possible to prepare a graphene oxide that does not cause a decrease in physical properties compared to the case of using a conventional strong acid even a short time of 80 minutes or less There are advantages to it.
  • the graphene oxide manufacturing method comprises the step of mixing the graphite and metal carbonate heat treatment in a short time, without the use of strong acid, it is possible to manufacture the graphene oxide in a simple method There is this.
  • the graphite injected in the heat treatment step may perform the graphene oxide production reaction in various particle size range
  • the present invention is not limited to the particle size range of graphite.
  • the graphite may have a particle size of 10 to 40000 ⁇ m, more specifically 30 to 2000 ⁇ m, but the present invention is not limited thereto.
  • the metal carbonate added in the heat treatment step is melted at the reaction temperature in accordance with the process characteristics of the present invention, it is possible to produce graphene oxide without limiting the particle size, non-limiting example, 10 to 40000 ⁇ m, more Specifically, the thickness may be 30 to 2000 ⁇ m, but the present invention is not limited thereto.
  • the graphene oxide manufacturing method according to an embodiment of the present invention may further include a cleaning step of cleaning the primary oxide generated through the heat treatment after the heat treatment step.
  • the washing may use one or two or more selected from water, C1 to C4 alcohol and aqueous acid solution, and can be used without limitation in the case of a solution used for washing in general.
  • the graphene oxide manufacturing method according to an embodiment of the present invention may perform a cleaning step through a weakly acidic cleaning liquid in view of dissolving and removing metal oxides that are impurities included in the primary oxide. .
  • the metal oxide as an impurity that may be included in the primary oxide may be one or two or more selected from Li 2 O, Na 2 O, and K 2 O, and a weakly acidic cleaning solution for removing the above-described metal oxide basic.
  • a weakly acidic cleaning solution for removing the above-described metal oxide basic.
  • the acid compound included in the weakly acidic cleaning solution may specifically use inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, or phosphoric acid in order to prevent a problem of impurities remaining in graphene oxide, but the present invention is not limited thereto.
  • the washing step may be performed through an aqueous solution of inorganic acid of 0.5 to 5% by weight, preferably 0.5 to 3% by weight, and further, water and Alternately, the inorganic acid aqueous solution may be used for washing, but the present invention is not limited thereto.
  • the present invention also provides graphene oxide, the graphene oxide according to the present invention may be prepared by the graphene oxide production method according to an embodiment of the present invention.
  • Graphene oxide according to an embodiment of the present invention may have a carbon / oxygen atom ratio of 0.1 to 3.0, more specifically 0.15 to 2.
  • the zeta potential of the aqueous solution of graphene oxide at a pH of 5 to 6 may be -20 to -50 mV. Preferably, it may be -30 to -50, more preferably -40 to -50, but is not limited thereto. This means that the surface potential is similar to graphene oxide prepared using Hummer's method or Modified Hummer's method, which is conventionally used, and that oxygen-containing functional groups are introduced into graphene through oxidation.
  • graphene oxide having the same zeta potential can be prepared as compared to the conventional method, and thus, it is easily applied to various articles such as electronic devices, coating materials, and fibers. It can be used as applicable material.
  • the present invention also provides a method for producing reduced graphene oxide, the method for producing reduced graphene oxide according to the present invention includes reducing the graphene oxide prepared by the method for producing graphene oxide according to an embodiment of the present invention. do.
  • the reduction can be used without limitation in the case of the reduction method of the commonly used graphene oxide, the present invention is not limited thereto.
  • Graphene oxide was prepared using Brodie's method, and detailed conditions are summarized in Table 1.
  • Graphene oxide was prepared using the Hummer's method, and detailed conditions are summarized in Table 1.
  • Graphene oxide was prepared using Modified Hummer's method using concentrated sulfuric acid as a solvent and potassium permanganate as an oxidant, and detailed conditions are summarized in Table 1.
  • Graphene oxide was prepared using Modified Hummer's method using concentrated sulfuric acid as a solvent and potassium permanganate and sodium nitrate as oxidants, and detailed conditions are summarized in Table 1.
  • the element analyzer was measured using Flash 1112, Thermo Fisher Scientific, Germany, oxidized each element by the dynamic flash combustion method and quantified by TCD detector, and each element was separated through a column and graphene oxide The percentage of elements was calculated by determining the amounts (%) of C, O, H, and N contained in the compound.
  • the surface of the graphene oxide prepared by the method according to Example 1 was analyzed by AFM (atomic microscope), TEM (transmission electron microscope) and SEM (scanning electron microscope) and shown in FIG.
  • the graphene oxide prepared by the method according to Example 1 of the present invention is formed in a single layer, which is difficult to derive from other methods except the conventional Hummers method, the graphene oxide of a single layer It can be expected that the graphene can be produced more excellent physical properties after reduction after the production.
  • Graphene oxide prepared by the method according to Example 1, Example 2, Example 3 and Comparative Example 3 was subjected to C1s XPS (Thermo scientific, ESCA Probe), Raman analysis (Renishaw, 514 nm, Ar + ionlaser), X-ray Analyze by diffraction analysis (Rigaku Ultima IV X-ray diffractometer with Cu K ⁇ radiation at a scanning rate of 5 ° C min -1 ), thermal stability analysis and FT-IR (FT-IR-2501PC, SHIMADZU), respectively.
  • C1s XPS Thermo scientific, ESCA Probe
  • Raman analysis Renishaw, 514 nm, Ar + ionlaser
  • X-ray Analyze by diffraction analysis Raku Ultima IV X-ray diffractometer with Cu K ⁇ radiation at a scanning rate of 5 ° C min -1
  • thermal stability analysis FT-IR (FT-IR-2501PC, SHIMADZU), respectively.
  • 1M 2 X means Example 1, 2M 2 X means Example 2, 3M 2 X means Example 3, 2-1M 2 X, 2-2M 2 X, 2-3M 2 X was experimented by varying the weight ratio of graphite: Na 2 CO 3 , 2-1M 2 X is 1: 1, 2-2M 2 X is 1: 2, 2-3M 2 X is 1: 3 mixed in a mixing ratio Means that.
  • MSGO and H-GO obtained in Example 1 and Comparative Example 3 were reduced by heat treatment at 400 ° C. to obtain reduced graphene oxide (MSrGO H-rGO), respectively, and they were formed into a sheet to form their contact angles, reflectances, and absorbances. Measured and shown in FIG.
  • the graphene oxide prepared in Example 1 shows the Raman absorption peak most similar to the graphene oxide prepared using Hummer's method.
  • Example 1 and Comparative Example 3 show various absorption peaks by oxygen-containing functional groups in common, and these results are consistent with those of FIGS. 2 to 4.
  • the graphene oxide prepared in Example 1 has a form in which the carbon-carbon double bond peak is more distinct from the peak of the carbon-oxygen bond formed by the oxidation reaction, compared to the graphene oxide prepared in Comparative Example 3. Is showing.
  • Comparative Example 3 suggests that the oxygen-containing functional group is limited to a specific functional group, and thus the type is smaller in comparison with the various types of oxygen-containing functional groups. It is consistent with the result of FIG.
  • the reduced graphene oxide prepared by reducing the graphene oxide prepared according to the embodiment of the present invention may have a low reflectance and high absorbance. Black pigments with high absorbance and low reflectance can be applied to the display panel as a black matrix.

Abstract

The present invention relates to a method for producing graphene oxide comprising a step of performing heat treatment by mixing graphite and metal carbonate. The method for producing graphene oxide according to the present invention has an advantage of producing graphene oxide in a short time without using a strong acid. In addition, the present invention has an advantage of capable of producing single layer graphene oxide, which was difficult to find in production of graphene oxide except prior Hummer's method. Furthermore, a product included in an oxide produced primarily includes metal ions, and therefore, the present invention has an advantage of capable of easily cleaning impurities.

Description

산화그래핀 제조방법Graphene Oxide Manufacturing Method
본 발명은 금속 탄산염을 이용하여 산화그래핀을 제조하는 산화그래핀 제조방법에 관한 것이다.The present invention relates to a graphene oxide production method for producing graphene oxide using a metal carbonate.
그래핀은 탄소원자가 sp 2결합으로 벌집 형태의 구조를 갖는 신소재를 의미한다. 이러한 그래핀은 투명성, 전기전도성, 열전도성 및 두께 대비 기계강도가 우수한 장점이 있으며, 표면적 또한 넓은 장점이 있다. 이러한 장점에 따라 그래핀은 첨단 전자소자, 센서, 슈퍼 커패시터 및 태양전지 등의 다양한 첨단분야에 활용되고 있어, 관련 연구가 활발히 수행되고 있다.Graphene refers to a new material having a honeycomb structure in which carbon atoms are sp 2 bonds. Such graphene has the advantages of transparency, electrical conductivity, thermal conductivity, and mechanical strength in comparison with thickness, and also has a wide surface area. According to these advantages, graphene is used in various advanced fields such as advanced electronic devices, sensors, supercapacitors, and solar cells, and related research is being actively conducted.
이러한 그래핀의 생산 방법은 크게 기계적 박리법, 화학기상증착법, 에픽택셜성장법, 화학적 환원방법이 있다. 이들 중 저렴한 비용으로 상대적으로 대량 생산이 가능한 방법은 화학적 환원법이다. 구체적으로 화학적 환원법은 흑연을 산화시켜 산화그래핀을 제조한 뒤, 이를 다시 환원함으로써 환원 산화그래핀(Reduced graphene oxide, RGO)을 생산할 수 있으며, 공정의 특성상 그래핀의 대량 생산이 용이한 장점이 있다.Such graphene production methods include mechanical peeling, chemical vapor deposition, epitaxial growth, and chemical reduction. Among these methods, a relatively low mass production method is possible by chemical reduction. Specifically, the chemical reduction method produces graphene oxide by oxidizing graphite, and then reduces the graphene oxide, thereby producing reduced graphene oxide (RGO). have.
종래 산화그래핀을 제조하기 위한 방법으로는 Hummer법(Hummer’s method) 또는 Brodie법(Brodie’s method)가 있으며, 최근에는 Hummer법을 개량한 개량 Hummer법(Modified Hummer’s method)를 이용하는 것이 통상적이었다.Conventionally, the Hummer method (Hummer's method) or the Brodie method (Brodie's method) may be used to prepare graphene oxide. Recently, it has been common to use an improved Hummer method (Modified Hummer's method), which is an improvement of the Hummer method.
그러나 기존의 방법을 이용하는 경우, 진한 황산 또는 질산 상에서 산화반응을 수행하여 고농도의 황산 처리가 문제될 수 있으며, 진한 황산과 물과의 발열반응에 의해 폭발 위험이 있고, 많은 양의 폐수가 발생하는 이유로 정제공정이 매우 복잡해지는 문제점이 있다.However, if the conventional method is used, high concentration sulfuric acid treatment may be problematic by performing oxidation reaction on concentrated sulfuric acid or nitric acid, and there is a risk of explosion due to exothermic reaction between concentrated sulfuric acid and water, and a large amount of wastewater is generated. For this reason, there is a problem that the purification process is very complicated.
이에, 선행기술(CARBON 2013, 64, pp. 225~229)에서는 개선된 개량 Hummer법을 제공하는 것을 목적으로 하나, 여전히 진한 황산을 이용하여 환경문제를 유발하는 문제점이 있다.Therefore, the prior art (CARBON 2013, 64, pp. 225 ~ 229) is to provide an improved improved Hummer method, but there is still a problem causing environmental problems using concentrated sulfuric acid.
[선행기술문헌][Preceding technical literature]
[비특허문헌][Non-Patent Documents]
CARBON 2013, 64, pp. 225~229CARBON 2013, 64, pp. 225-229
본 발명의 목적은 고농도의 산성용액을 이용하지 않으면서도 산화그래핀을 제조할 수 있는 산화그래핀 제조방법을 제공하는 것이다.It is an object of the present invention to provide a graphene oxide production method capable of producing graphene oxide without using a high concentration of acidic solution.
본 발명의 다른 목적은 단시간 내에 산화그래핀을 경제적으로 제조할 수 있는 산화그래핀 제조방법을 제공하는 것이다.Another object of the present invention is to provide a graphene oxide production method that can economically produce graphene oxide in a short time.
본 발명의 또 다른 목적은 불순물이 쉽게 세정되어 세정과정이 간소화되며, 불순물을 거의 포함하지 않는 산화그래핀 제조방법을 제공하는 것이다.Still another object of the present invention is to provide a method for producing graphene oxide, in which impurities are easily washed to simplify the cleaning process and hardly contain impurities.
본 발명의 또 다른 목적은 건식공정으로 액체상 폐기물의 배출을 최소화한 산화그래핀 제조방법을 제공하는 것이다.Still another object of the present invention is to provide a method for producing graphene oxide, which minimizes the discharge of liquid waste in a dry process.
본 발명의 또 다른 목적은 단층의 산화그래핀을 제조할 수 있는 산화그래핀 제조방법을 제공하는 것이다.Still another object of the present invention is to provide a graphene oxide manufacturing method capable of producing a single layer of graphene oxide.
본 발명의 또 다른 목적은 결함이 최소화된 고품질의 산화그래핀 및 환원 산화그래핀을 제공하는 것이다.It is still another object of the present invention to provide high quality graphene oxide and reduced graphene oxide with minimal defects.
본 발명에 따른 산화그래핀의 제조방법은 흑연과 금속 탄산염을 혼합하여 열처리하는 단계를 포함한다.The method for producing graphene oxide according to the present invention includes a step of heat treatment by mixing graphite and metal carbonate.
본 발명의 일 실시예에 의한 산화그래핀 제조방법에 있어, 상기 열처리하는 단계는 건식 공정으로 수행될 수 있다.In the graphene oxide manufacturing method according to an embodiment of the present invention, the heat treatment may be performed by a dry process.
본 발명의 일 실시예에 의한 산화그래핀 제조방법에 있어, 상기 열처리하는 단계의 열처리는 500 내지 1200 ℃에서 수행될 수 있다.In the graphene oxide manufacturing method according to an embodiment of the present invention, the heat treatment step of the heat treatment may be performed at 500 to 1200 ℃.
본 발명의 일 실시예에 의한 산화그래핀 제조방법에 있어, 상기 열처리단계에서 혼합되는 흑연 : 금속 탄산염의 중량비는 1:1 내지 10일 수 있다.In the graphene oxide manufacturing method according to an embodiment of the present invention, the weight ratio of graphite: metal carbonate mixed in the heat treatment step may be 1: 1 to 10.
본 발명의 일 실시예에 의한 산화그래핀 제조방법에 있어, 상기 금속 탄산염에 포함되는 금속은 1족 금속일 수 있다.In the graphene oxide manufacturing method according to an embodiment of the present invention, the metal included in the metal carbonate may be a Group 1 metal.
본 발명의 일 실시예에 의한 산화그래핀 제조방법에 있어, 상기 열처리단계는 10분 이상 수행될 수 있다.In the graphene oxide manufacturing method according to an embodiment of the present invention, the heat treatment step may be performed for 10 minutes or more.
본 발명의 일 실시예에 의한 산화그래핀 제조방법에 있어, 상기 열처리단계 후 생성된 1차 산화물을 0.5 내지 5 중량% 무기산 수용액으로 세정하는 세정단계를 더 포함할 수 있다.In the graphene oxide manufacturing method according to an embodiment of the present invention, the primary oxide produced after the heat treatment step may further comprise a washing step of washing with 0.5 to 5% by weight inorganic acid aqueous solution.
본 발명은 또한 산화그래핀을 제공하며, 본 발명에 따른 산화그래핀은 본 발명의 일 실시예에 의한 산화그래핀 제조방법으로 제조된 것일 수 있다.The present invention also provides graphene oxide, the graphene oxide according to the present invention may be prepared by the graphene oxide production method according to an embodiment of the present invention.
본 발명의 일 실시예에 따른 산화그래핀은 산화그래핀에 포함된 탄소/산소 원자 비율이 1.75 이상일 수 있다.Graphene oxide according to an embodiment of the present invention may be a carbon / oxygen atom ratio contained in the graphene oxide is 1.75 or more.
본 발명의 일 실시예에 따른 산화그래핀 제조방법에서 상기 산화그래핀은 물 1 ㎖에 분산된 산화그래핀 1 ㎎을 기준으로 한 제타전위가 -20 내지 -50 mV일 수 있다.In the graphene oxide manufacturing method according to an embodiment of the present invention, the zeta potential of the graphene oxide based on 1 mg of graphene oxide dispersed in 1 ml of water may be -20 to -50 mV.
본 발명은 또한 환원 산화그래핀 제조방법을 제공하며, 본 발명에 따른 환원 산화그래핀 제조방법은 본 발명의 일 실시예에 의한 산화그래핀 제조방법으로 제조된 산화그래핀을 환원하는 단계를 포함하여 제조된 것일 수 있다.The present invention also provides a method for producing reduced graphene oxide, the method for producing reduced graphene oxide according to the present invention includes the step of reducing the graphene oxide prepared by the method for producing graphene oxide according to an embodiment of the present invention. It may be prepared by.
본 발명은 흑연과 금속 탄산염을 건식공정 하에서 열처리함으로써 고농도의 산성용액을 이용하지 않으면서도, 단시간 내에 산화그래핀을 제조할 수 있는 장점이 있다. 또한, 종래 Hummer’s method를 제외한 산화그래핀의 제조에서 찾아보기 어려웠던 단층 산화그래핀을 제조할 수 있는 장점이 있다. 나아가, 1차적으로 생성된 산화물에 포함되는 생성물은 금속 이온을 포함하여, 불순물의 세정이 쉬운 장점이 있다.The present invention has the advantage that the graphene oxide can be produced in a short time without using a high concentration of acidic solution by heat-treating the graphite and metal carbonate in a dry process. In addition, there is an advantage in that it is possible to manufacture a single layer graphene oxide, which was difficult to find in the manufacture of graphene oxide except the Hummer's method. Furthermore, the product included in the oxide produced primarily includes metal ions, so that impurities can be easily cleaned.
도 1은 본 발명의 실시예에 의해 제조된 산화그래핀의 표면을 분석하여 도시한 것이다.Figure 1 shows the analysis of the surface of the graphene oxide prepared by the embodiment of the present invention.
도 2는 본 발명의 실시예 및 비교예에 의한 산화그래핀의 X선 광전자 분광법(X-ray Photoelectron Spectroscopy, XPS) 분석을 도시한 것이다.FIG. 2 illustrates X-ray photoelectron spectroscopy (XPS) analysis of graphene oxide according to examples and comparative examples of the present invention.
도 3은 본 발명의 실시예 및 비교예에 의한 산화그래핀의 라만 스펙트럼을 도시한 것이다.Figure 3 shows the Raman spectrum of the graphene oxide according to the Examples and Comparative Examples of the present invention.
도 4는 본 발명의 실시예 및 비교예에 의한 산화그래핀의 X선 회절 스펙트럼(XRD)을 도시한 것이다.4 shows X-ray diffraction spectra (XRD) of graphene oxide according to examples and comparative examples of the present invention.
도 5는 본 발명의 실시예 및 비교예에 의한 산화그래핀의 열 안정성을 도시한 것이다.Figure 5 shows the thermal stability of the graphene oxide according to the Examples and Comparative Examples of the present invention.
도 6은 본 발명의 실시예 및 비교예에 의한 산화그래핀의 FT-IR을 측정하고 도시한 것이다.6 is a graph illustrating the FT-IR of graphene oxide according to Examples and Comparative Examples of the present invention.
도 7은 본 발명의 실시예, 비교예 및 이들을 각각 열처리를 통해 환원하여 제조된 환원그래핀으로 제조된 접촉각, 반사율 및 흡광도를 측정하고 이를 도시한 것이다.FIG. 7 shows examples of the present invention, a comparative example, and a measurement of contact angle, reflectance, and absorbance of reduced graphene prepared by reducing them through heat treatment, respectively.
이하 본 발명에 따른 산화그래핀 제조방법에 대해 상세히 설명한다. 이때, 사용되는 기술 용어 및 과학 용어에 있어서 다른 정의가 없다면, 이 발명이 속하는 기술 분야에서 통상의 지식을 가진 자가 통상적으로 이해하고 있는 의미를 가지며, 하기의 설명에서 본 발명의 요지를 불필요하게 흐릴 수 있는 공지 기능 및 구성에 대한 설명은 생략한다.Hereinafter, a graphene oxide manufacturing method according to the present invention will be described in detail. In this case, unless there is another definition in the technical terms and scientific terms used, it has the meaning that is commonly understood by those of ordinary skill in the art, unnecessarily obscure the subject matter of the present invention in the following description Description of known functions and configurations that may be omitted.
또한 명세서 및 첨부된 청구범위에서 사용되는 단수 형태는 문맥에서 특별한 지시가 없는 한 복수 형태도 포함하는 것으로 의도할 수 있다.Also, the singular forms used in the specification and the appended claims may be intended to include the plural forms as well, unless the context clearly indicates otherwise.
본 발명에서 특별한 언급 없이 사용된 % 및 비(ratio)의 단위는 중량% 및 중량비를 의미하며, 달리 정의되지 않는 한 전체 조성물 중 어느 하나의 성분이 조성물 내에서 차지하는 중량%를 의미한다.Units of% and ratio used without particular mention in the present invention mean weight% and weight ratio, and unless otherwise defined, means weight% of any one of the total compositions in the composition.
본 발명에 따른 산화그래핀의 제조방법은 흑연과 금속 탄산염을 혼합하여 열처리하는 단계를 포함한다.The method for producing graphene oxide according to the present invention includes a step of heat treatment by mixing graphite and metal carbonate.
본 발명은 산화그래핀의 제조방법을 제공하며, 본 발명에 따른 산화그래핀의 제조방법은 흑연과 금속 탄산염을 혼합하여 열처리하는 단계를 포함한다.The present invention provides a method for producing graphene oxide, and the method for producing graphene oxide according to the present invention includes a step of mixing and heat treating graphite and metal carbonate.
본 발명에 따른 산화그래핀 제조방법은 황산, 질산 또는 인산 등과 같은 강산을 이용하지 않으면서도, 단시간 내에 산화그래핀의 제조가 가능하고, 불순물의 제거가 용이한 장점이 있다.The graphene oxide production method according to the present invention is capable of producing graphene oxide in a short time without using a strong acid such as sulfuric acid, nitric acid or phosphoric acid, and has the advantage of easy removal of impurities.
구체적으로, 종래 널리 알려진 Hummer’s method 등은 진한 황산과 같은 용매 상에서 산화반응을 수행함으로써, 폐액으로 배출되는 진한 황산의 처리가 어렵고, 이를 희석하는 과정에서 환경문제를 유발하는 문제점이 있다. 나아가, 통상적으로 사용되는 Hummer’s method 등은 최소 2시간, 통상적으로 8 시간 이상의 긴 반응시간을 필요로 하여, 산화그래핀의 합성에 장시간이 소요되는 문제점이 있으며, 진한 황산을 용매로 이용하는 경우 제조되는 산화그래핀에 황이 0.05 내지 0.5 % 가량 불순물로 포함될 수 있는 문제점이 있다.Specifically, Hummer's method, which is widely known in the art, is difficult to treat concentrated sulfuric acid discharged to waste liquid by performing an oxidation reaction on a solvent such as concentrated sulfuric acid, and there is a problem of causing environmental problems in the process of diluting it. Furthermore, Hummer's method, which is commonly used, requires a long reaction time of at least 2 hours, typically 8 hours or more, and thus requires a long time for synthesizing graphene oxide. There is a problem that sulfur may be included in the graphene oxide as impurities about 0.05 to 0.5%.
그러나 본 발명에 의한 산화그래핀 제조방법은 강산을 필요로 하지 않아 폐액의 처리 문제가 발생하지 않으며, 산화그래핀의 생산 시 추가적으로 발생하는 폐액 처리 비용을 절감할 수 있다. 또한, 짧은 시간동안의 열처리로도 산화그래핀의 제조가 가능하여 단기간 내에 다량의 산화그래핀을 생산할 수 있는 장점이 있다. 나아가 본 발명에 의한 산화그래핀 제조방법은 흑연의 열처리 후 포함되는 불순물이 금속 산화물이어서, 비교적 세정이 용이하여, 세정과정의 일부 생략으로도 순도 높은 산화그래핀을 생산할 수 있는 장점이 있다.However, the graphene oxide manufacturing method according to the present invention does not require a strong acid does not cause the problem of the treatment of waste liquid, it is possible to reduce the waste liquid treatment costs additionally generated during the production of graphene oxide. In addition, it is possible to produce graphene oxide even by a heat treatment for a short time, there is an advantage that can produce a large amount of graphene oxide in a short time. Furthermore, the method for producing graphene oxide according to the present invention is an impurity included after the heat treatment of the graphite is a metal oxide, relatively easy to clean, there is an advantage that can produce a high purity graphene even by eliminating some of the cleaning process.
본 발명의 일 실시예에 의한 산화그래핀 제조방법에서 상기 열처리하는 단계는 건식 공정으로 수행될 수 있다. 본 발명의 일 실시예에 의한 산화그래핀 제조방법은, 상술한 강산 용매 없이 건식 공정으로 산화 반응을 수행함으로써 강산에 의한 환경 오염문제를 예방하고, 폐액을 최소화할 수 있는 장점이 있다.In the graphene oxide manufacturing method according to an embodiment of the present invention, the heat treatment may be performed by a dry process. Graphene oxide manufacturing method according to an embodiment of the present invention, by performing the oxidation reaction in a dry process without the above-mentioned strong acid solvent has the advantage of preventing the environmental pollution problem by strong acid, and minimize the waste fluid.
또한, 종래 산화 그래핀의 제조로 Hummer’s method가 다수 이용된 것은, 강산을 이용한 환경문제 등에도 불구하고 단층의 산화그래핀을 제조할 수 있는 장점이 있기 때문이었다. 그러나 본 발명에 의한 산화 그래핀 제조방법은 건식 공정으로 강산 폐수의 배출 없이도, 단층의 산화그래핀을 제조할 수 있는 장점이 있으며, 이러한 단층의 산화 그래핀으로 추후 제조되는 환원 산화그래핀의 비표면적 및 전기 전도도 등의 특성을 현저히 향상시킬 수 있는 장점이 있다.In addition, the Hummer's method has been used in the manufacture of graphene oxide in the prior art because it has the advantage of producing graphene oxide in a single layer despite environmental problems using a strong acid. However, the graphene oxide manufacturing method according to the present invention has a merit that a single layer of graphene oxide can be produced without the discharge of strong acid wastewater by a dry process, and the ratio of the reduced graphene oxide which is subsequently produced by such a single layer of graphene oxide There is an advantage that can significantly improve characteristics such as surface area and electrical conductivity.
구체적으로, 본 발명의 일 실시예에 의한 산화그래핀 제조방법에서 상기 열처리 하는 단계의 열처리는 500 내지 1200 ℃, 구체적으로는 600 내지 1000 ℃, 더욱 구체적으로는 700 내지 900 ℃일 수 있다. 상술한 온도 범위에서 산화그래핀의 합성 효율을 향상시키면서도, 지나치게 고온에 의한 산화그래핀의 생산효율 저하를 예방할 수 있는 장점이 있다.Specifically, the heat treatment of the heat treatment step in the graphene oxide manufacturing method according to an embodiment of the present invention may be 500 to 1200 ℃, specifically 600 to 1000 ℃, more specifically 700 to 900 ℃. While improving the synthesis efficiency of graphene oxide in the above-described temperature range, there is an advantage that can be prevented from lowering the production efficiency of graphene oxide due to excessively high temperature.
상기 열처리 단계에서 분위기(atmosphere)는 산소를 포함하는 분위기라면 제한받지 사용될 수 있으며, 비한정적인 일 예로 공기일 수 있다.Atmosphere in the heat treatment step may be used without limitation as long as the atmosphere containing oxygen, it may be air as one non-limiting example.
본 발명의 일 실시예에 의한 산화그래핀 제조방법에서, 상기 열처리단계에서 혼합되는 흑연 : 금속 탄산염의 중량비는 1:1 내지 10, 구체적으로는 1:1 내지 6, 더욱 구체적으로는 1:1 내지 4일 수 있다. 상술한 범위에서 산화그래핀의 생산 수율을 높이면서도, 과도한 금속 탄산염 함량으로 추후 제조되는 산화그래핀에 불순물이 함유되는 문제를 예방할 수 있다. 나아가 금속 탄산염에 포함되는 금속은 1족 금속일 수 있으며, 구체적으로는 리튬, 나트륨 및 칼륨에서 선택되는 하나 또는 둘 이상일 수 있으며, 더욱 구체적으로 금속 탄산염은 Li 2CO 3, Na 2CO 3 및 K 2CO 3 등에서 선택되는 하나 또는 둘 이상을 포함할 수 있으나, 이는 제1족 금속 탄산염의 일 예일뿐이므로, 본 발명이 이에 제한되는 것은 아니다.In the graphene oxide production method according to an embodiment of the present invention, the weight ratio of graphite to the metal carbonate mixed in the heat treatment step is 1: 1 to 10, specifically 1: 1 to 6, more specifically 1: 1 To 4 may be. While increasing the production yield of graphene oxide in the above-described range, it is possible to prevent the problem that impurities are contained in the graphene oxide to be produced later with excessive metal carbonate content. Further, the metal included in the metal carbonate may be a Group 1 metal, specifically, one or two or more selected from lithium, sodium, and potassium, and more specifically, the metal carbonate may be Li 2 CO 3 , Na 2 CO 3, and K. It may include one or two or more selected from 2 CO 3 and the like, but this is only an example of the Group 1 metal carbonate, the present invention is not limited thereto.
본 발명의 일 실시예에 의한 산화그래핀 제조방법에서, 열처리단계는 흑연의 산화반응에 의해 산화그래핀을 생성할 수 있는 시간 동안 제한 없이 수행할 수 있으며 일례로 10분 이상 수행될 수 있다. 좋게는 10분 내지 120분, 더욱 좋게는 20 내지 80분간 수행될 수 있으나 이는 바람직한 일예일뿐 이에 제한받지 않는다. 본 발명의 일 실시예에 의한 산화그래핀 제조방법은 종래 알려진 산화그래핀 제조방법과 달리, 80분 이하의 단시간 반응으로도 종래 강산을 이용한 경우 대비 물성 저하가 발생하지 않는 산화그래핀을 제조할 수 있는 장점이 있다.In the graphene oxide manufacturing method according to an embodiment of the present invention, the heat treatment step may be carried out without limitation during the time to produce the graphene oxide by the oxidation reaction of the graphite, for example may be performed for 10 minutes or more. Preferably 10 to 120 minutes, more preferably 20 to 80 minutes can be carried out but this is a preferred example and not limited thereto. Graphene oxide manufacturing method according to an embodiment of the present invention, unlike the conventionally known graphene oxide manufacturing method, it is possible to prepare a graphene oxide that does not cause a decrease in physical properties compared to the case of using a conventional strong acid even a short time of 80 minutes or less There are advantages to it.
다시 말해, 본 발명의 일 실시예에 의한 산화그래핀 제조방법은 흑연과 금속 탄산염을 혼합하여 단시간 내에 열처리하는 단계를 포함함으로써 강산을 이용하지 않으면서도, 간단한 방법으로 산화그래핀의 제조가 가능한 장점이 있다.In other words, the graphene oxide manufacturing method according to an embodiment of the present invention comprises the step of mixing the graphite and metal carbonate heat treatment in a short time, without the use of strong acid, it is possible to manufacture the graphene oxide in a simple method There is this.
본 발명의 일 실시예에 의한 산화 그래핀 제조방법에서, 상기 열처리단계에서 투입되는 흑연은 다양한 입도 범위에서 산화 그래핀 제조반응을 수행할 수 있으며, 본 발명이 흑연의 입도 범위에 제한되는 것은 아니다. 구체적으로, 상기 흑연의 입도는 10 내지 40000 ㎛, 더욱 구체적으로는 30 내지 2000 ㎛일 수 있으나, 본 발명이 이에 제한되는 것은 아니다. 또한, 상기 열처리단계에서 투입되는 금속 탄산염은, 본 발명의 공정 특성 상 반응온도에서 용융되므로, 입자 크기에 제한 없이 산화 그래핀의 제조가 가능하며, 비제한적인 일 예로, 10 내지 40000 ㎛, 더욱 구체적으로는 30 내지 2000 ㎛일 수 있으나, 이에 본 발명이 제한되지 않음은 물론이다.In the graphene oxide manufacturing method according to an embodiment of the present invention, the graphite injected in the heat treatment step may perform the graphene oxide production reaction in various particle size range, the present invention is not limited to the particle size range of graphite. . Specifically, the graphite may have a particle size of 10 to 40000 μm, more specifically 30 to 2000 μm, but the present invention is not limited thereto. In addition, the metal carbonate added in the heat treatment step is melted at the reaction temperature in accordance with the process characteristics of the present invention, it is possible to produce graphene oxide without limiting the particle size, non-limiting example, 10 to 40000 ㎛, more Specifically, the thickness may be 30 to 2000 μm, but the present invention is not limited thereto.
본 발명의 일 실시예에 의한 산화그래핀 제조방법은 상기 열처리하는 단계 후 열처리를 거쳐 생성된 1차 산화물을 세정하는 세정단계를 더 포함할 수 있다. 이때 세정은 물, C1 내지 C4의 알코올 및 산 수용액에서 선택되는 하나 또는 둘 이상을 이용할 수 있으며, 통상적으로 세정에 이용되는 용액인 경우 제한 없이 이용이 가능하다. 더욱 좋게는, 본 발명의 일 실시예에 의한 산화그래핀 제조방법은, 1차 산화물 내에 포함될 수 있는 불순물인 금속 산화물을 용해하여 제거하기 위한 관점에서 약산성의 세정액을 통해 세정단계를 수행할 수 있다. 구체적으로 상기 1차 산화물에 포함될 수 있는 불순물인 금속 산화물은 Li 2O, Na 2O 및 K 2O에서 선택되는 하나 또는 둘 이상일 수 있으며, 염기성의 상술한 금속 산화물의 제거를 위하여 약산성의 세정용액을 이용할 수 있다. 이때 약산성의 세정용액에 포함되는 산 화합물은 구체적으로, 산화그래핀에 불순물이 잔류하는 문제를 예방하기 위하여 염산, 질산, 황산 또는 인산 등의 무기산을 이용할 수 있으나 본 발명이 이에 제한되는 것은 아니다. 더욱 좋게는, 본 발명의 일 실시예에 의한 산화그래핀 제조방법에서 상기 세정단계는 0.5 내지 5 중량%, 좋게는 0.5 내지 3 중량%의 무기산 수용액을 통하여 세정을 수행할 수 있으며, 나아가 물과 무기산 수용액을 번갈아가면서 세정에 이용할 수 있으나, 본 발명이 이에 제한되는 것은 아니다.The graphene oxide manufacturing method according to an embodiment of the present invention may further include a cleaning step of cleaning the primary oxide generated through the heat treatment after the heat treatment step. In this case, the washing may use one or two or more selected from water, C1 to C4 alcohol and aqueous acid solution, and can be used without limitation in the case of a solution used for washing in general. More preferably, the graphene oxide manufacturing method according to an embodiment of the present invention may perform a cleaning step through a weakly acidic cleaning liquid in view of dissolving and removing metal oxides that are impurities included in the primary oxide. . Specifically, the metal oxide as an impurity that may be included in the primary oxide may be one or two or more selected from Li 2 O, Na 2 O, and K 2 O, and a weakly acidic cleaning solution for removing the above-described metal oxide basic. Can be used. In this case, the acid compound included in the weakly acidic cleaning solution may specifically use inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, or phosphoric acid in order to prevent a problem of impurities remaining in graphene oxide, but the present invention is not limited thereto. More preferably, in the graphene oxide production method according to an embodiment of the present invention, the washing step may be performed through an aqueous solution of inorganic acid of 0.5 to 5% by weight, preferably 0.5 to 3% by weight, and further, water and Alternately, the inorganic acid aqueous solution may be used for washing, but the present invention is not limited thereto.
본 발명은 또한 산화그래핀을 제공하며, 본 발명에 의한 산화그래핀은 본 발명의 일 실시예에 의한 산화그래핀 제조방법으로 제조된 것일 수 있다.The present invention also provides graphene oxide, the graphene oxide according to the present invention may be prepared by the graphene oxide production method according to an embodiment of the present invention.
본 발명의 일 실시예에 의한 산화그래핀은 탄소/산소 원자 비율이 0.1 내지 3.0, 더욱 구체적으로는 0.15 내지 2일 수 있다. 또한 pH가 5 내지 6 인 조건에서 산화그래핀의 수용액상의 제타 전위는 -20 내지 -50 mV일 수 있다. 바람직하게는 -30 내지 -50, 보다 바람직하게는 -40 내지 -50일 수 있으나 이에 제한받지 않는다. 이는 종래 다수 이용되던 Hummer’s method 또는 Modified Hummer’s method를 이용해 제조된 산화그래핀과 대비하여, 표면 전위가 유사한 값을 나타내는 것으로 산화반응을 통해 산소 함유 작용기가 그래핀에 도입되었음을 의미한다. 즉, 단시간 내에 강산을 이용하지 않고 산화그래핀을 제조하더라도 종래 방법과 대비하여 제타 전위가 동등한 수준의 산화그래핀이 제조될 수 있고, 이를 통해 전자소자, 코팅소재, 섬유 등 다양한 물품에 용이하게 적용 가능한 소재로 활용될 수 있음을 시사한다.Graphene oxide according to an embodiment of the present invention may have a carbon / oxygen atom ratio of 0.1 to 3.0, more specifically 0.15 to 2. In addition, the zeta potential of the aqueous solution of graphene oxide at a pH of 5 to 6 may be -20 to -50 mV. Preferably, it may be -30 to -50, more preferably -40 to -50, but is not limited thereto. This means that the surface potential is similar to graphene oxide prepared using Hummer's method or Modified Hummer's method, which is conventionally used, and that oxygen-containing functional groups are introduced into graphene through oxidation. That is, even if graphene oxide is produced without using a strong acid within a short time, graphene oxide having the same zeta potential can be prepared as compared to the conventional method, and thus, it is easily applied to various articles such as electronic devices, coating materials, and fibers. It can be used as applicable material.
본 발명은 또한 환원 산화그래핀 제조방법을 제공하며, 본 발명에 의한 환원 산화그래핀 제조방법은 본 발명의 일 실시예에 의한 산화그래핀 제조방법으로 제조된 산화그래핀을 환원하는 단계를 포함한다. 이때 환원은 통상적으로 이용되는 산화그래핀의 환원방법인 경우 제한 없이 이용이 가능하며, 본 발명이 이에 제한되는 것은 아니다.The present invention also provides a method for producing reduced graphene oxide, the method for producing reduced graphene oxide according to the present invention includes reducing the graphene oxide prepared by the method for producing graphene oxide according to an embodiment of the present invention. do. In this case, the reduction can be used without limitation in the case of the reduction method of the commonly used graphene oxide, the present invention is not limited thereto.
이하 본 발명을 실시예에 의해 구체적으로 설명한다. 아래에서 설명하는 실시예는 발명의 이해를 돕기 위한 것일 뿐, 본 발명이 실시예에 한정되지 않는다.Hereinafter, the present invention will be described in detail by way of examples. The embodiments described below are merely to aid the understanding of the invention, and the present invention is not limited to the embodiments.
[실시예 1]Example 1
평균입도가 2000 ㎛인 흑연 0.5 g과 Li 2CO 3 2.0 g을 알루미나 도가니에 넣고 잘 섞어준다. 혼합된 흑연과 금속 탄산염 혼합물을 850 ℃에서 30분간 열처리한다. 열처리가 끝난 반응물을 물에 녹이고, 물로 원심분리를 이용하여 한차례 세척한 후, 1 중량% 염산으로 한번 세척한다. 다시 물로 세 번 원심분리를 이용하여 세척하고, 세척이 완료된 산화그래핀을 상온에서 건조시키거나, 물에 분산된 상태로 보관한다.0.5 g of graphite having an average particle size of 2000 μm and 2.0 g of Li 2 CO 3 are added to an alumina crucible and mixed well. The mixed graphite and metal carbonate mixture is heat treated at 850 ° C. for 30 minutes. The heat treated reaction product is dissolved in water, washed once with centrifugation with water, and then washed once with 1 wt% hydrochloric acid. Again washed with centrifugation three times with water, and the washed graphene oxide is dried at room temperature or stored in a state dispersed in water.
[실시예 2]Example 2
실시예 1과 같은 방법으로 제조하되, Li 2CO 3 대신 Na 2CO 3를 동량 혼합하여 산화그래핀을 제조하였다.Prepared in the same manner as in Example 1, but instead of Li 2 CO 3 Na 2 CO 3 by mixing the same amount to prepare a graphene oxide.
[실시예 3]Example 3
실시예 1과 같은 방법으로 제조하되, Li 2CO 3 대신 K 2CO 3를 동량 혼합하여 산화그래핀을 제조하였다.Prepared in the same manner as in Example 1, but instead of Li 2 CO 3 K 2 CO 3 by mixing the same amount to prepare a graphene oxide.
[비교예 1]Comparative Example 1
Brodie’s method를 이용하여 산화그래핀을 제조하였으며, 상세한 조건은 표 1로 정리하였다.Graphene oxide was prepared using Brodie's method, and detailed conditions are summarized in Table 1.
[비교예 2]Comparative Example 2
Hummer’s method를 이용하여 산화그래핀을 제조하였으며, 상세한 조건은 표 1로 정리하였다.Graphene oxide was prepared using the Hummer's method, and detailed conditions are summarized in Table 1.
[비교예 3]Comparative Example 3
진한 황산을 용매로 이용하며, 과망간산칼륨을 산화제로 이용하는 Modified Hummer’s method를 이용하여 산화그래핀을 제조하였으며, 상세한 조건은 표 1로 정리하였다.Graphene oxide was prepared using Modified Hummer's method using concentrated sulfuric acid as a solvent and potassium permanganate as an oxidant, and detailed conditions are summarized in Table 1.
[비교예 4][Comparative Example 4]
진한 황산을 용매로 이용하며, 과망간산칼륨 및 질산나트륨을 산화제로 이용하는 Modified Hummer’s method를 이용하여 산화그래핀을 제조하였으며, 상세한 조건은 표 1로 정리하였다.Graphene oxide was prepared using Modified Hummer's method using concentrated sulfuric acid as a solvent and potassium permanganate and sodium nitrate as oxidants, and detailed conditions are summarized in Table 1.
[실험예 1]Experimental Example 1
<탄소/산소 원자비율(C/O ratio) 측정><Measurement of carbon / oxygen ratio (C / O ratio)>
실시예 1 및 비교예 1 내지 4에 의해 제조된 산화그래핀을 원소 분석을 통하여 분석하였으며, 그 결과를 표 1로 나타내었다.Graphene oxide prepared in Example 1 and Comparative Examples 1 to 4 was analyzed by elemental analysis, and the results are shown in Table 1.
이때, 원소 분석기는 Flash 1112, Thermo Fisher Scientific, Germany를 사용하여 측정하였으며, Dynamic flash combustion method 에 의한 각 원소들을 각각 산화하여 TCD detector로 정량하고, 각 원소들은 Column을 통과하여 분리가 되고 산화 그래핀에 포함되어 있는 C, O, H, N 등의 양(%)를 결정하여 원소의 비율을 계산하였다.At this time, the element analyzer was measured using Flash 1112, Thermo Fisher Scientific, Germany, oxidized each element by the dynamic flash combustion method and quantified by TCD detector, and each element was separated through a column and graphene oxide The percentage of elements was calculated by determining the amounts (%) of C, O, H, and N contained in the compound.
표 1을 참고하면, 본 발명의 실시예 1에 의해 제조된 산화그래핀의 탄소/산소 원자비율은 진한 황산 등의 산 용매를 사용한 경우와 크게 차이가 나지 않음을 확인할 수 있다.Referring to Table 1, it can be seen that the carbon / oxygen atomic ratio of graphene oxide prepared by Example 1 of the present invention is not significantly different from that of an acid solvent such as concentrated sulfuric acid.
용매menstruum 산화제Oxidant 반응시간Reaction time 불순물impurities 폐액 배출량Waste discharge 탄소/산소 원자비율Carbon / oxygen atomic ratio
실시예 1Example 1 -(건식공정)-(Dry process) Li 2CO 3 Li 2 CO 3 30분30 minutes Li 2OLi 2 O 약 3 L3 L 1.821.82
실시예 2Example 2 -(건식공정)-(Dry process) Na 2CO 3 Na 2 CO 3 30분30 minutes Na 2ONa 2 O 약 3 L3 L 0.670.67
실시예 3Example 3 -(건식공정)-(Dry process) K 2CO 3 K 2 CO 3 30분30 minutes K 2OK 2 O 약 3 L3 L 0.180.18
비교예 1Comparative Example 1 H 2SO 4,HNO 3 H 2 SO 4, HNO 3 KClO 3 KClO 3 10 시간10 hours ClO 2 ClO 2 약 10 L10 L 2.162.16
비교예 2Comparative Example 2 H 2SO 4 H 2 SO 4 NaNO 3,KMnO 4 NaNO 3 , KMnO 4 2-8 시간2-8 hours NO x,Mn 2O 7 NO x , Mn 2 O 7 약 10 L10 L 2.252.25
비교예 3Comparative Example 3 H 2SO 4 H 2 SO 4 KMnO 4 KMnO 4 8 시간8 hours Mn 2O 7 Mn 2 O 7 약 10 L10 L 1.681.68
비교예 4Comparative Example 4 H 2SO 4 H 2 SO 4 NaNO 3,KMnO 4 NaNO 3 , KMnO 4 120 시간120 hours NO x,Mn 2O 7 NO x , Mn 2 O 7 약 10 L10 L 2.232.23
[실험예 2]Experimental Example 2
<제타전위 측정>Zeta potential measurement
실시예 1 및 비교예 3에 의해 제조된 산화그래핀의 제타전위를 633nm의 He-Ne 레이저를 이용한 표면 전위 측정기(Zetasizer 3000HS, Malvern; 10mW)를 통해 측정하였다. 구체적으로 실시예 1 및 비교예 3의 산화그래핀을 각각 물에 1mg/mL 농도로 분산된 조건(pH=5.5)에서 제타전위를 측정하였으며, 그 결과를 표 2로 나타내었다.The zeta potential of graphene oxide prepared by Example 1 and Comparative Example 3 was measured by a surface potential meter (Zetasizer 3000HS, Malvern; 10mW) using a He-Ne laser of 633nm. Specifically, the zeta potential was measured under the conditions (pH = 5.5) in which the graphene oxides of Example 1 and Comparative Example 3 were dispersed in water at a concentration of 1 mg / mL, respectively, and the results are shown in Table 2.
제타 전위(mV)Zeta potential (mV)
실시예 1Example 1 -43.5-43.5
비교예 3Comparative Example 3 -44.2-44.2
표 2를 참고하면, 통상적으로 이용되는 Modified Hummer’s method를 이용한 경우와 대비하여 제타 전위에서 큰 차이를 나타내지 않음을 확인할 수 있으며, 이를 토대로 강산을 사용하지 않으면서도 유사한 물성의 산화그래핀을 생산할 수 있음을 확인할 수 있다. 나아가, 실시예와 같이 약산을 이용한 간단한 세척만으로도 순도 높은 산화그래핀을 제조할 수 있음을 확인할 수 있다.Referring to Table 2, it can be seen that there is no significant difference in zeta potential compared to the case of using the commonly used Modified Hummer's method. Based on this, it is possible to produce graphene oxide of similar properties without using a strong acid. can confirm. Furthermore, it can be seen that high purity graphene oxide can be produced by simple washing with a weak acid as in the example.
[실험예 3]Experimental Example 3
<산화그래핀의 표면 분석>Surface analysis of graphene oxide
실시예 1에 의한 방법으로 제조된 산화그래핀의 표면을 AFM(원자력 현미경), TEM(투과전자현미경) 및 SEM(주사 전자현미경)으로 분석하고 도 1로 나타내었다.The surface of the graphene oxide prepared by the method according to Example 1 was analyzed by AFM (atomic microscope), TEM (transmission electron microscope) and SEM (scanning electron microscope) and shown in FIG.
도 1을 참고하면, 본 발명의 실시예 1에 의한 방법으로 제조된 산화 그래핀이 단층으로 형성됨을 확인할 수 있으며, 이는 종래 Hummers method를 제외한 다른 방법에서는 도출하기 어려운 효과로, 단층의 산화 그래핀 제조로 추후 환원 후 더욱 물성이 우수한 그래핀을 제조할 수 있음을 예측할 수 있다.Referring to Figure 1, it can be seen that the graphene oxide prepared by the method according to Example 1 of the present invention is formed in a single layer, which is difficult to derive from other methods except the conventional Hummers method, the graphene oxide of a single layer It can be expected that the graphene can be produced more excellent physical properties after reduction after the production.
[실험예 4]Experimental Example 4
<산화그래핀의 특성 분석><Characteristic analysis of graphene oxide>
실시예 1, 실시예 2, 실시예 3 및 비교예 3에 의한 방법으로 제조된 산화그래핀을 C1s XPS(Thermo scientific, ESCA Probe), Raman 분석(Renishaw, 514 nm, Ar +ionlaser), X선 회절분석(Rigaku Ultima IV X-ray diffractometer with Cu Kα radiation at a scanning rate of 5°C min -1), 열안정성 분석 및 FT-IR(FT-IR-2501PC, SHIMADZU)을 통해 분석하고 각각 도 2 내지 도 6으로 나타내었다.Graphene oxide prepared by the method according to Example 1, Example 2, Example 3 and Comparative Example 3 was subjected to C1s XPS (Thermo scientific, ESCA Probe), Raman analysis (Renishaw, 514 nm, Ar + ionlaser), X-ray Analyze by diffraction analysis (Rigaku Ultima IV X-ray diffractometer with Cu Kα radiation at a scanning rate of 5 ° C min -1 ), thermal stability analysis and FT-IR (FT-IR-2501PC, SHIMADZU), respectively. To FIG. 6.
도 2 내지 6에서, 1M 2X는 실시예 1, 2M 2X는 실시예 2, 3M 2X는 실시예 3을 의미하며, 2-1M 2X, 2-2M 2X, 2-3M 2X는 흑연 : Na 2CO 3의 중량비를 달리하여 실험한 것으로, 2-1M 2X는 1:1, 2-2M 2X는 1:2, 2-3M 2X는 1:3의 혼합비로 혼합된 것을 의미한다.2 to 6, 1M 2 X means Example 1, 2M 2 X means Example 2, 3M 2 X means Example 3, 2-1M 2 X, 2-2M 2 X, 2-3M 2 X Was experimented by varying the weight ratio of graphite: Na 2 CO 3 , 2-1M 2 X is 1: 1, 2-2M 2 X is 1: 2, 2-3M 2 X is 1: 3 mixed in a mixing ratio Means that.
[실험예 5]Experimental Example 5
<접촉각, 반사율 및 흡광도 측정><Measurement of contact angle, reflectance and absorbance>
실시예 1과 비교예 3에서 얻어진 MSGO와 H-GO을 400℃ 열처리로 환원하여 각각 환원산화그래핀(MSrGO H-rGO)을 얻고, 이를 시트상으로 형성하여, 이들의 접촉각, 반사율 및 흡광도를 측정하고 도 7로 나타내었다.MSGO and H-GO obtained in Example 1 and Comparative Example 3 were reduced by heat treatment at 400 ° C. to obtain reduced graphene oxide (MSrGO H-rGO), respectively, and they were formed into a sheet to form their contact angles, reflectances, and absorbances. Measured and shown in FIG.
도 2의 결과를 참조해보면, 실시예 1에 의해 제조된 산화그래핀은 비교예 3에 의해 제조된 산화그래핀과 대비하여 탄소-탄소 이중결합이 피크가 산화반응에 의해 형성된 탄소-산소 결합의 피크와 분명히 구분된 형태를 보여주고 있다. 이러한 구분한 형태로 볼 때, 비교예 3은 다양한 형태의 산소 함유 작용기가 폭넓게 그래핀 분자 상에 포함되어 있음을 보여주고 있고, 실시예 1에서는 산소 함유 작용기가 특정 작용기로 제한되어 종류가 보다 적다는 것을 시사하고 있다. 또한, 실시예 1의 산화물에 해당하는 부분의 피크 값이 낮은 것을 볼 때, 비교예 3 대비 상대적으로 산화된 탄소의 숫자는 적으면서도, 그래핀에 표면 영역에 해당하는 탄소-탄소 이중결합의 비율은 높은 것을 확인할 수 있다. 한편, 고농도의 산성용액을 사용하지 않는 실시예 1을 통해서 제조된 산화그래핀이 종래 Hummer’s method를 이용하여 제조된 산화 그래핀과 대비해 물성적인 면에서도 유사한 것을 확인할 수 있다.Referring to the results of Figure 2, the graphene oxide prepared by Example 1 compared with the graphene oxide prepared by Comparative Example 3 carbon-carbon double bond peak of the carbon-oxygen bond formed by the oxidation reaction It is clearly distinguished from the peaks. In this distinctive form, Comparative Example 3 shows that various types of oxygen-containing functional groups are widely contained on the graphene molecules, and in Example 1, oxygen-containing functional groups are limited to specific functional groups, and thus are of fewer types. Suggesting that. In addition, when the peak value of the portion corresponding to the oxide of Example 1 is low, the ratio of carbon-carbon double bonds corresponding to the surface region in graphene, while the number of oxidized carbon relatively small compared to Comparative Example 3 Is high. On the other hand, it can be seen that the graphene oxide prepared through Example 1, which does not use a high concentration of acidic solution, is similar in terms of physical properties as compared with graphene oxide prepared using a conventional Hummer's method.
도 3의 결과를 참조해보면, 실시예 1에 의해 제조된 산화 그래핀이 Hummer’s method를 이용하여 제조된 산화 그래핀과 가장 유사한 라만 흡광피크를 나타내고 있다.Referring to the results of FIG. 3, the graphene oxide prepared in Example 1 shows the Raman absorption peak most similar to the graphene oxide prepared using Hummer's method.
도 4의 XRD 결과를 참조해보면, 층간에 산소 작용기가 도입됨에 따라 층간 박리가 발생하여 약 10° 부근에서 산화 그래핀에서 특징적으로 나타나는 회절 피크를 확인할 수 있다. 따라서 도 2 내지 도 4의 결과를 종합해 볼 때 본 발명은 종래 Hummer’s method과 동등한 수준으로 단층 수준의 산화그래핀을 제조할 수 있음을 확인할 수 있다.Referring to the XRD results of FIG. 4, it can be seen that diffraction peaks characteristic of graphene oxide at about 10 ° occur due to the intercalation as oxygen groups are introduced into the layers. Therefore, when combining the results of Figures 2 to 4 it can be seen that the present invention can produce a single layer graphene oxide at a level equivalent to the conventional Hummer's method.
도 5의 열안정성 실험 결과를 참조해 보면, 실시예 1에 의해 생성된 산화그래핀이 비교예 3의 종래 Hummer’s method를 이용하여 제조된 산화 그래핀과 가장 유사한 거동을 나타냄을 확인할 수 있다.Referring to the thermal stability test results of Figure 5, it can be seen that the graphene oxide produced by Example 1 exhibits the most similar behavior to the graphene oxide prepared using the conventional Hummer's method of Comparative Example 3.
도 6의 FT-IR 실험 결과를 참조해 보면, 실시예 1 및 비교예 3은 산소 함유 작용기에 의한 다양한 흡광 피크를 공통적으로 보여주고 있으며, 이러한 결과는 상기 도 2 내지 도 4의 결과와 일치하는 것이다. 그러나 실시예 1에 의해 제조된 산화그래핀은 비교예 3에 의해 제조된 산화그래핀과 대비하여 탄소-탄소 이중결합이 피크가 산화반응에 의해 형성된 탄소-산소 결합의 피크와 좀더 구분된 형태를 보여주고 있다. 이러한 구분한 형태로 볼 때, 비교예 3은 다양한 형태의 산소 함유 작용기가 포함되어 있음에 비해 실시예 1에서는 산소 함유 작용기가 특정 작용기로 제한되어 종류가 보다 적다는 것을 시사하고 있으며, 이러한 결과는 도 2의 결과와 일치하는 것이다.Referring to the results of the FT-IR experiment of FIG. 6, Example 1 and Comparative Example 3 show various absorption peaks by oxygen-containing functional groups in common, and these results are consistent with those of FIGS. 2 to 4. will be. However, the graphene oxide prepared in Example 1 has a form in which the carbon-carbon double bond peak is more distinct from the peak of the carbon-oxygen bond formed by the oxidation reaction, compared to the graphene oxide prepared in Comparative Example 3. Is showing. In view of such a distinctive form, Comparative Example 3 suggests that the oxygen-containing functional group is limited to a specific functional group, and thus the type is smaller in comparison with the various types of oxygen-containing functional groups. It is consistent with the result of FIG.
도 7의 결과로 볼 때, 비교예 3 대비 실시예 1에서 제조된 산화 그래핀의 접촉각이 높은 것을 알 수 있으며, 이러한 결과는 각각 이들을 환원하여 환원산화그래핀을 형성한 경우에도 비슷한 경향으로 나타남을 확인할 수 있다. As a result of Figure 7, it can be seen that the contact angle of the graphene oxide prepared in Example 1 compared to Comparative Example 3 is high, these results are shown to have a similar tendency even when the reduced graphene oxide is formed by reducing them, respectively. can confirm.
반사율 및 흡광도 측면에서 볼 때 본 발명의 실시예에 의해 제조된 산화 그래핀을 환원하여 제조한 환원산화그래핀이 반사율이 낮으면서, 흡광도가 높음을 확인할 수 있다. 흡광도가 높으면서 반사율이 낮은 검정 안료는 디스플레이 패널에 black matrix 로 적용 할 수 있을 것으로 보여진다.In terms of reflectance and absorbance, the reduced graphene oxide prepared by reducing the graphene oxide prepared according to the embodiment of the present invention may have a low reflectance and high absorbance. Black pigments with high absorbance and low reflectance can be applied to the display panel as a black matrix.

Claims (12)

  1. 흑연과 금속 탄산염을 혼합하여 열처리하는 단계를 포함하는 산화그래핀 제조방법.Graphene oxide manufacturing method comprising the step of heat treatment by mixing the graphite and metal carbonate.
  2. 제1항에 있어서,The method of claim 1,
    상기 열처리하는 단계는 건식 공정으로 수행되는 산화그래핀 제조방법.The heat treatment step is a graphene oxide manufacturing method performed by a dry process.
  3. 제1항에 있어서,  The method of claim 1,
    상기 열처리하는 단계의 열처리는 500 내지 1200 ℃에서 수행되는 산화그래핀 제조방법.The heat treatment of the heat treatment step is a graphene oxide manufacturing method performed at 500 to 1200 ℃.
  4. 제1항에 있어서,The method of claim 1,
    상기 열처리단계에서 혼합되는 흑연 : 금속 탄산염의 중량비는 1:1 내지 10인 산화그래핀 제조방법.Graphite mixed in the heat treatment step: the weight ratio of the metal carbonate is 1: 1 to 10 graphene oxide production method.
  5. 제1항에 있어서,The method of claim 1,
    상기 금속 탄산염에 포함되는 금속은 1족 금속인 산화그래핀 제조방법.The metal included in the metal carbonate is a group 1 metal graphene oxide manufacturing method.
  6. 제1항에 있어서,The method of claim 1,
    상기 열처리단계는 10분 이상 수행되는 산화그래핀 제조방법.The heat treatment step is a graphene oxide manufacturing method that is performed for 10 minutes or more.
  7. 제 1항에 있어서,The method of claim 1,
    상기 열처리단계 후 생성된 1차 산화물을 0.5 내지 5 중량% 무기산 수용액으로 세정하는 세정단계를 더 포함하는 산화그래핀 제조방법.Graphene oxide manufacturing method further comprises a washing step of washing the primary oxide produced after the heat treatment step with 0.5 to 5% by weight aqueous solution of inorganic acid.
  8. 제1항 내지 제7항 중 어느 한 항의 방법으로 제조된 산화그래핀.Graphene oxide prepared by the method of any one of claims 1 to 7.
  9. 제8항에 있어서,The method of claim 8,
    상기 산화그래핀은 산화그래핀에 포함된 탄소/산소 원자 비율이 1.75 이상인 산화그래핀.The graphene oxide is a graphene oxide graphene oxide is more than 1.75 in the graphene oxide.
  10. 제8항에 있어서,The method of claim 8,
    상기 산화그래핀은 물 1 ㎖에 분산된 산화그래핀 1 ㎎을 기준으로 한 제타전위가 -20 내지 -50 mV인 산화그래핀.The graphene oxide has a zeta potential of -20 to -50 mV based on 1 mg of graphene oxide dispersed in 1 ml of water.
  11. 제1항 내지 제7항 중 어느 한 항의 제조방법으로 제조된 산화그래핀을 환원하는 단계를 포함하는 고비표면적의 환원 산화그래핀 제조방법.A method for producing reduced graphene oxide having a high specific surface area comprising the step of reducing the graphene oxide prepared by the method of any one of claims 1 to 7.
  12. 제11항에 의한 환원 산화그래핀을 포함하는 도전성 잉크 조성물.A conductive ink composition comprising the reduced graphene oxide according to claim 11.
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