WO2017188527A1 - Three-dimensional graphene structure synthesizing method using spraying - Google Patents

Three-dimensional graphene structure synthesizing method using spraying Download PDF

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WO2017188527A1
WO2017188527A1 PCT/KR2016/012002 KR2016012002W WO2017188527A1 WO 2017188527 A1 WO2017188527 A1 WO 2017188527A1 KR 2016012002 W KR2016012002 W KR 2016012002W WO 2017188527 A1 WO2017188527 A1 WO 2017188527A1
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spray
graphene structure
rgo
dimensional
dimensional graphene
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PCT/KR2016/012002
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French (fr)
Korean (ko)
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안호선
김지훈
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인천대학교 산학협력단
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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
    • C01B32/184—Preparation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
    • C02F1/4691—Capacitive deionisation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/16—Pore diameter
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/13—Energy storage using capacitors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present invention relates to a method for synthesizing a three-dimensional graphene structure using spray injection, and more particularly, by spraying a reduced graphene oxide (RGO) solution directly by spraying onto a heated target surface to overheat evaporation;
  • RGO reduced graphene oxide
  • the present invention relates to a method for efficiently manufacturing a self-assembled foam-like three-dimensional graphene structure having micropores in a simple manner without additional processing by establishing optimum process conditions.
  • the three-dimensional graphene structure synthesized according to the present invention is a graphene having excellent electrical conductivity and thermal conductivity is formed in three dimensions to maximize the specific surface area, energy storage material including the electrode of the supercapacitor, heat transfer material related to nuclear power generation, It can be applied to various fields such as desalination process.
  • Graphene an allotrope of carbon, is an atomic-level 2D structured sheet-like material with excellent electrical, thermal, mechanical, and optical properties, resulting in energy storage devices, batteries, field-effect transistors, and optoelectronics. It is emerging as an advanced carbon material that can be applied to a wide range of fields including organic optoelectronic devices and chemical sensors.
  • composite materials such as graphene, graphene / conductive polymer, graphene / metal oxide, graphene / carbon nanotube, and graphene / metal nanoparticles are various electrode materials such as supercapacitors, touch screens, transparent electrodes, etc. It is used for the purpose of improving the characteristics.
  • the Hummers method known as the most common liquid stripping technique, is a technique of oxidizing graphite and then peeling it in water to produce single layer graphene oxide (GO), which contains graphite as a strong oxidizing agent.
  • GO graphene oxide
  • the graphene layers are oxidized and the graphene is formed by separating the layers due to the repulsive force present between the oxide layers.
  • the water-soluble graphene oxide (GO) is functionalized by epoxide groups, hydroxyl groups, carboxyl groups and other oxygen moieties (carbonyl, phenol, lactone, quinone, etc.).
  • graphene oxide is electrically insulated, and reduced graphene oxide (RGO), which has been converted to conductivity by applying chemical or thermal treatment thereto, is widely used as an electric and electronic material.
  • the present invention is to solve the problems of the prior art as described above, to provide a method for efficiently synthesizing a foam-like (foam-like) three-dimensional graphene structure having a micro-pores in a simple manner without additional processes Let it be technical problem.
  • the solvent is a distilled water single solvent or a two-component solvent mixed with distilled water and a volatile organic solvent,
  • the concentration of the reduced graphene oxide (RGO) colloidal solution is 0.1 ⁇ 1.0 mg / mL
  • the substrate is heated and maintained at a temperature of 220 ⁇ 350 °C,
  • the spray spray is repeated one time or a plurality of times
  • the temperature of the substrate is controlled by a Proportional-Integral-Derivative controller (PID) controller to recover the temperature back to the set temperature when the temperature drops as the spray jet and the droplet evaporate.
  • PID Proportional-Integral-Derivative controller
  • the self-assembly reduced graphene oxide (RGO) particles are characterized in that to form a foam-like (foam-like) three-dimensional structure having micropores,
  • Step a) is a step of preparing an RGO colloid solution in which reduced graphene oxide (RGO) is uniformly dispersed in a solvent as a precursor for synthesizing a three-dimensional graphene structure.
  • RGO reduced graphene oxide
  • the reduced graphene oxide (RGO) may be prepared and provided according to conventional methods in the art.
  • a graphite powder e.g., powder size: ⁇ 20 ⁇ m; 0.5 ⁇ 1.0 ⁇ m
  • a reducing agent such as 4 , NaOH or NaBH 4, and then heating to 60-100 ° C. for 2-6 hours to reduce.
  • the solvent may be used without particular limitation, a kind that can sufficiently disperse the RGO, and can be easily evaporated by the heated substrate.
  • distilled water is used alone, or a two-component solvent system in which a volatile organic solvent is mixed with distilled water is used.
  • a general dispersing method in the art such as ultrasonication may be additionally performed.
  • Step b) is spray spraying the RGO colloidal solution prepared in step a) onto a heated substrate surface in the form of micro droplets (independent droplets) using a predetermined apparatus (see FIG. 2) equipped with a spray nozzle. .
  • the microdroplets that come into contact with the heated substrate by this spray spray cause instantaneous evaporation of the solvent on the substrate surface (more specifically, overheating) and instantaneous condensation of RGO particles in the droplets, during which the microdroplets are overheated.
  • the RGO particles existing at the interface are self-assembly to form a foam-shaped three-dimensional graphene structure (see FIG. 4).
  • the present invention uses the principle that the RGO particles are self-assembled along the interface of the microdroplets overheating, as the coffee powder and salt crystals remain on the surface after the evaporation of coffee or brine (see FIG. 10).
  • the spray injection of the RGO solution is repeated one or more times.
  • the coating thickness on the substrate can be controlled by adjusting the number of powders (total injection amount) of the RGO solution. Specifically, it was confirmed through experiments that the coating thickness increases and the pore size decreases as the number of powders increases.
  • the spray spraying may be performed by repeating the RGO solution at a concentration of 0.1 mg / mL twice (30 mL in total), each 30 mL of injection amount.
  • the substrate is heated to be maintained at a temperature of 220 ⁇ 350 °C (preferably, 250 °C). If the temperature of the substrate surface is less than 220 °C may not be a smooth overheating of the spray-injected micro droplets, if it exceeds 350 °C may cause a problem that the coating amount is greatly reduced.
  • the temperature of the substrate is controlled by a Proportional-Integral-Derivative controller (PID controller). Specifically, when the temperature of the substrate surface decreases according to the spray injection and the evaporation of droplets, the substrate surface is controlled by the PID controller.
  • the temperature of is configured to automatically recover to a predetermined temperature (220 ⁇ 350 °C).
  • the method of spray-injecting an RGO solution is not specifically limited, What is necessary is just to inject
  • Ultrasonic (nozzle) spraying apparatus can freely form micrometer-scale droplets having a uniform size distribution from the RGO solution through ultrasonic vibration, in which the RGO is uniformly dispersed in the solvent. .
  • the size of the micro independent droplets may be adjusted to an average of 10 ⁇ m through a spray nozzle (see FIG. 1). That is, the size of the droplets is preferably adjusted to have a relatively larger size than the final RGO particles obtained on the substrate, as the solvent contained in the droplets evaporate only the RGO particles contained in the droplets remain self-assembly than the size of the original droplets This is because small sized RGO particles are formed into a structure.
  • the concentration of the RGO solution is appropriate 0.1 ⁇ 1.0 mg / mL. If the concentration is less than 0.1 mg / mL, the amount of RGO may be too small, making it difficult to form a three-dimensional graphene structure of a desired size to thickness smoothly. If the amount of RGO is excessively greater than 1.0 mg / mL, As the pore size of the structure becomes relatively large, it may be difficult to realize the effect of the specific surface area increase due to the activation of the micropores.
  • the concentration of the RGO solution when using a single solvent of distilled water as the solvent, it is preferable to adjust the concentration of the RGO solution to 0.1 mg / mL in terms of maximizing micropores.
  • distilled water may be used alone, but in some cases, by using a binary mixture in which distilled water and a volatile organic solvent are mixed and adjusting the mole fraction thereof, Pore properties can be controlled to suit specific applications.
  • the volatile organic solvent may be an alcohol-based organic solvent, such as methanol (Methanol) or ethanol (Ethanol).
  • the mole fraction of the volatile organic solvent in the RGO solution may be 0.05 ⁇ 0.7, the pore size decreases as the mole fraction of the volatile organic solvent in the RGO solution of distilled water is increased, the nanoporous (Nanoporous from 0.2 or more mole fraction) Experimentally confirmed that the three-dimensional graphene structure of the structure) is formed.
  • the kind of the substrate on which the RGO solution is spray sprayed is not particularly limited, and for example, a silicon (Si) substrate, a glass substrate or a polymer substrate may be used.
  • a silicon (Si) substrate can be used.
  • the concentration of the RGO solution, the substrate temperature, the number of spin-offs, the type of solvent and the mixing ratio are the main control variables, but the injection height (distance between the substrate and the nozzle), the injection pressure, and the size of the ejection hole (Orifice size) as necessary. Etc. can be further suitably adjusted.
  • Self-assembled RGO particles according to the present invention form a foam-like (foam-like) three-dimensional structure having micropores, wherein the size of the micropores is 0.1 ⁇ 10 ⁇ m level, the average size is It may be several ⁇ m or less.
  • the three-dimensional graphene structure synthesized according to the present invention may be used as a material in various fields such as an energy storage device, a heat transfer device, or a desalination device.
  • the energy storage element may include a capacitor, various batteries (eg, secondary cells, solar cells), fuel cells, and the like.
  • the three-dimensional graphene structure synthesized according to the present invention can be directly applied to the next-generation energy storage field, and by maximizing the specific surface area by synthesizing it in three dimensions with excellent electrical conductivity of graphene, high energy density and output power It can be used very ideally as an electrode material of supercapacitors where density is required at the same time.
  • an oxidation functional group formed on the surface of the graphene fragment may act as a catalyst to increase charge and discharge rates. .
  • the three-dimensional graphene structure synthesized according to the present invention is a nuclear power and thermal power generation field where the management of thermal energy is the core by the high thermal conductivity characteristics of the graphene (document value: 5000W / mK, copper: 400W / mK) It can be used as a heat transfer material of.
  • the heat diffusion ability of the graphene and the water absorption ability of the three-dimensional structure there is an advantage that can improve the critical heat flux, the limit of boiling performance.
  • the three-dimensional graphene structure synthesized according to the present invention can be used as an electrode of the capacitive deionization (CDI) process, in this case by selectively removing only the target ions to maximize the desalination efficiency, reducing the power cost
  • CDI capacitive deionization
  • the three-dimensional graphene structure synthesized according to the present invention will be widely applicable to catalyst applications, optical materials, biomaterials, solar materials, and the like.
  • the present invention spray sprays the RGO solution directly onto the target surface, so that the 3D graphene structure can be mass-produced in a simple and easy manner without additional processes such as a framework or etching such as polymer or metal.
  • the present invention by controlling the various process parameters associated with the formation of the graphene structure by spray injection, it is possible to apply directly to the material of various fields such as next-generation energy storage device (especially supercapacitor), heat transfer device and desalination device Three-dimensional structure can be formed.
  • next-generation energy storage device especially supercapacitor
  • heat transfer device especially heat transfer device
  • desalination device Three-dimensional structure can be formed.
  • FIG. 1 is a schematic diagram showing a method for synthesizing a three-dimensional graphene structure through micro-independent droplet injection according to the present invention.
  • FIG. 2 is a schematic diagram of an apparatus used for micro independent droplet injection according to the present invention.
  • Figure 3 is a photograph showing an example of the spray automatic injection device used in the present invention.
  • SEM scanning electron microscope
  • 5 to 9 are scanning electron microscopes showing the shapes of the synthesized three-dimensional graphene structures with different concentrations of graphene in the RGO solution, spin water, substrate surface temperature and solvent composition according to embodiments of the present invention. SEM) image.
  • the RGO colloidal solution was spray-sprayed onto the heated substrate surface in the form of droplets through a device such as FIG. 2 to synthesize a 3D graphene structure.
  • the pore size and micropore activity of the synthesized three-dimensional graphene structure decreased, and the pore size of the solution was 0.1 mg / mL. It was. This means that the pore size and activity of the structure can be controlled by changing the concentration of the graphene precursor solution for synthesizing the three-dimensional graphene structure.
  • the RGO colloidal solution was spray-sprayed onto the heated substrate surface in the form of droplets through a device such as FIG. 2 to synthesize a 3D graphene structure.
  • the coating amount significantly decreased, and an optimal three-dimensional structure was formed at the substrate temperature of 250 ° C. This means that the surface temperature of the substrate where superheat evaporation affects the morphology of the three-dimensional graphene structure.
  • the RGO colloidal solution was spray-sprayed onto the heated substrate surface in the form of droplets through a device such as FIG. 2 to synthesize a 3D graphene structure.
  • the three-dimensional graphene structure is a key material in the next generation energy storage field such as supercapacitors, and is not only a high value-added industry itself, but also a next-generation infrastructure industry in the country where high-density energy sources are required (renewable energy generation and hydrogen and electric vehicle fields). It is also closely related to).
  • the present invention is a method for mass production of high-quality three-dimensional graphene structure in a simple and easy manner, widely applied as a material for improving the performance of various devices such as next-generation energy storage devices, heat transfer devices, power generation devices and desalination devices. This will be possible.

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Abstract

The present invention relates to a three-dimensional graphene structure synthesizing method using spraying and, more specifically, to a method which uses a spray to directly spray a reduced graphene oxide (RGO) solution in the form of liquid droplets onto a heated target surface so as to superheat and evaporate the solution, while establishing optimal related process conditions, so that the method can efficiently manufacture a self-assembled foam-like three-dimensional graphene structure having fine pores in a simple manner without an additional process. A three-dimensional graphene structure synthesized according to the present invention has graphene, which has excellent electrical conductivity and excellent thermal conductivity and is three-dimensionally formed, and thus has a maximized specific surface area. Therefore, the three-dimensional graphene structure can be applied to various fields, such as an electrode of a supercapacitor, an energy storage material, a heat transfer material related to nuclear power generation, and a desalting process.

Description

스프레이 분사를 이용한 ３차원 그래핀 구조체의 합성방법Synthesis of 3D Graphene Structure Using Spray Injection
본 발명은 스프레이 분사를 이용한 3차원 그래핀 구조체의 합성방법에 관한 것으로, 더욱 상세하게는 스프레이를 이용하여 환원된 산화그래핀(RGO) 용액을 가열된 타겟 표면에 직접 액적 분사하여 과열증발시킴과 더불어 관련된 최적의 공정조건들을 수립함으로써, 추가 공정 없는 간단한 방식으로 미세기공을 갖는 자가조립 폼 형상(Foam-like)의 3차원 그래핀 구조체를 효율적으로 제조할 수 있는 방법에 관한 것이다.The present invention relates to a method for synthesizing a three-dimensional graphene structure using spray injection, and more particularly, by spraying a reduced graphene oxide (RGO) solution directly by spraying onto a heated target surface to overheat evaporation; In addition, the present invention relates to a method for efficiently manufacturing a self-assembled foam-like three-dimensional graphene structure having micropores in a simple manner without additional processing by establishing optimum process conditions.
본 발명에 따라 합성된 3차원 그래핀 구조체는 전기전도도 및 열전도도가 우수한 그래핀이 3차원으로 형성되어 비표면적이 극대화되는바, 슈퍼커패시터의 전극을 비롯한 에너지 저장 소재, 원자력 발전 관련 열전달 소재, 탈염 공정 등 다양한 분야에 적용될 수 있다.The three-dimensional graphene structure synthesized according to the present invention is a graphene having excellent electrical conductivity and thermal conductivity is formed in three dimensions to maximize the specific surface area, energy storage material including the electrode of the supercapacitor, heat transfer material related to nuclear power generation, It can be applied to various fields such as desalination process.
탄소의 동소체인 그래핀(Graphene)은 원자 수준의 두께를 지닌 2D 구조의 시트형 물질로서 전기적, 열적, 기계적 및 광학적 특성이 탁월하여 에너지 저장 소자, 배터리, 전계효과 트랜지스터(Field-effect transistor), 광전자 소자(Organic optoelectronic device) 및 화학센서를 비롯한 광범위한 분야에 적용될 수 있는 첨단 탄소 소재로 부각되고 있다. 또한, 최근에는 그래핀, 그래핀/전도성 고분자, 그래핀/금속산화물, 그래핀/탄소나노튜브, 그래핀/금속 나노입자 등의 복합소재들이 다양한 전극 재료로서 슈퍼커패시터, 터치 스크린, 투명전극 등의 특성 개선을 목적으로 활용되고 있다.Graphene, an allotrope of carbon, is an atomic-level 2D structured sheet-like material with excellent electrical, thermal, mechanical, and optical properties, resulting in energy storage devices, batteries, field-effect transistors, and optoelectronics. It is emerging as an advanced carbon material that can be applied to a wide range of fields including organic optoelectronic devices and chemical sensors. In addition, recently, composite materials such as graphene, graphene / conductive polymer, graphene / metal oxide, graphene / carbon nanotube, and graphene / metal nanoparticles are various electrode materials such as supercapacitors, touch screens, transparent electrodes, etc. It is used for the purpose of improving the characteristics.
이러한 다양하고도 잠재적인 적용을 위해, 많은 경우 산업적 규모로 생산될 수 있는 수용성의 고유(Pristine) 그래핀이 요구되고 있다. 안정한 그래핀 분산액이 일단 구비되면, 딥-코팅, 드롭-코팅, 스핀-코팅, 스프레이-코팅, 진공 여과, Langmuir-Blodgett, Layer-by-Layer(LbL) 및 전기영동 전착 기술과 같은 다양한 용액-공정 기술을 이용하여 나노미터에서 수십 마이크로미터에 이르는 두께의 균일한 그래핀 박막을 매우 간단하게 제작할 수 있다.For these diverse and potential applications, water-soluble pristine graphene is required, which in many cases can be produced on an industrial scale. Once a stable graphene dispersion is in place, various solutions such as dip-coating, drop-coating, spin-coating, spray-coating, vacuum filtration, Langmuir-Blodgett, Layer-by-Layer (LbL) and electrophoretic electrodeposition techniques- Process technology makes it very simple to produce uniform graphene films with thicknesses ranging from nanometers to tens of micrometers.
가장 통상적인 액상 박리 기술로 알려진 하머스법(Hummers method)은 그래파이트를 산화시킨 후 수중에서 박리하여 단일층 그래핀 산화물(Graphene Oxide; GO)을 제조하는 기술로서, 이는 그래파이트를 강한 산화제를 포함하는 수용액과 접촉하는 과정에서 그래핀층들이 산화되고 산화층들 사이에 존재하는 반발력으로 인해 층이 분리되면서 그래핀이 형성되는 메커니즘을 이용한다. 이때, 수용성 그래핀 산화물(GO)은 에폭사이드기, 하이드록실기, 카르복실기 및 기타 산소 부분(카보닐, 페놀, 락톤, 퀴논 등)에 의해 기능화된다. 한편, 그래핀 산화물은 전기적으로 절연인바, 이에 화학적 또는 열적 처리를 가하여 전도성으로 전환시킨 환원된 산화그래핀(Reduced Graphene Oxide; RGO)이 전기·전자 소재로 많이 활용되고 있다.The Hummers method, known as the most common liquid stripping technique, is a technique of oxidizing graphite and then peeling it in water to produce single layer graphene oxide (GO), which contains graphite as a strong oxidizing agent. In contact with the aqueous solution, the graphene layers are oxidized and the graphene is formed by separating the layers due to the repulsive force present between the oxide layers. At this time, the water-soluble graphene oxide (GO) is functionalized by epoxide groups, hydroxyl groups, carboxyl groups and other oxygen moieties (carbonyl, phenol, lactone, quinone, etc.). Meanwhile, graphene oxide is electrically insulated, and reduced graphene oxide (RGO), which has been converted to conductivity by applying chemical or thermal treatment thereto, is widely used as an electric and electronic material.
그러나, 종래의 통상적인 그래핀 소재는 기공이 없거나 활성이 부족한 2차원적 구조로 주로 제공되어 전극 소재 등으로 적용시 우수한 소자 성능을 구현하는데 소정의 한계가 있었다. 예를 들어, 높은 에너지 밀도와 출력 밀도를 동시에 요구하는 슈퍼커패시터의 경우 우수한 전기전도도와 더불어 비표면적이 극대화된 전극 소재의 사용이 소자의 주요 성능을 결정하는 중요한 요소가 된다.However, conventional conventional graphene materials are mainly provided in a two-dimensional structure with no pores or lack of activity, and there are certain limitations in implementing excellent device performance when applied to electrode materials. For example, in the case of supercapacitors requiring high energy density and power density simultaneously, the use of an electrode material with a high specific surface area as well as good electrical conductivity is an important factor in determining the device's main performance.
이를 해결하고자, 그래핀을 3차원의 구조체로 합성하려는 시도들이 일부 진행되었다. 그러나, 이러한 기존의 3차원 그래핀 구조체 합성법들은 폴리머, 금속과 같은 골격체(Framework) 등을 필요로 하고, 추가의 식각 공정을 수행해야 하는 등 공정 상의 번거로움이 많았다.To solve this problem, some attempts have been made to synthesize graphene into a three-dimensional structure. However, these conventional three-dimensional graphene structure synthesis method requires a framework such as a polymer, a metal, etc., and the additional etching process has to be performed a lot of process hassles.
이에, 높은 전기전도도 및 열전도도 등 그래핀 고유의 유리한 특성을 보유하되 그 유효 비표면적이 극대화되어 소자의 성능 개선에 크게 기여할 수 있는 3차원(3D)의 그래핀 구조체, 및 이러한 3차원 그래핀 구조체를 골격체(Framework) 사용 및 식각 공정 등 추가적인 공정 없이 간단한 방식을 통해 효율적으로 합성할 수 있는 새로운 방법에 대한 개발이 요구되는 시점이다.Thus, it has a three-dimensional (3D) graphene structure, which possesses the advantages of graphene inherent characteristics such as high electrical conductivity and thermal conductivity, but the effective specific surface area is maximized, which can greatly contribute to the performance improvement of the device, and such three-dimensional graphene It is time to develop a new method for efficiently synthesizing a structure in a simple manner without additional processes such as using a framework and etching process.
본 발명은 상기와 같은 종래기술의 문제점을 해결하고자 한 것으로, 추가 공정 없는 간단한 방식으로 미세기공을 갖는 폼 형상(Foam-like)의 3차원 그래핀 구조체를 효율적으로 합성할 수 있는 방법을 제공하는 것을 기술적 과제로 한다.The present invention is to solve the problems of the prior art as described above, to provide a method for efficiently synthesizing a foam-like (foam-like) three-dimensional graphene structure having a micro-pores in a simple manner without additional processes Let it be technical problem.
상기한 기술적 과제를 달성하고자, 본 발명은In order to achieve the above technical problem, the present invention
a) 환원된 산화그래핀(Reduced Graphene Oxide; RGO)을 용매에 분산시켜 환원된 산화그래핀(RGO) 콜로이드 용액을 준비하는 단계; 및a) preparing a reduced graphene oxide (RGO) colloidal solution by dispersing reduced graphene oxide (RGO) in a solvent; And
b) 상기 환원된 산화그래핀(RGO) 콜로이드 용액을 스프레이 노즐(Spray nozzle)을 통해 마이크로 독립액적(Droplet)의 형태로 가열된 기판 표면 위에 스프레이 분사시켜, 환원된 산화그래핀(RGO) 입자들이 과열증발(Superheated evaporation)하는 마이크로 액적 계면을 따라 자가조립(Self-assembly)되도록 하는 단계;를 포함하며,b) spraying the reduced graphene oxide (RGO) colloidal solution onto a heated substrate surface in the form of micro-droplets through a spray nozzle, thereby reducing the reduced graphene oxide (RGO) particles. Including self-assembly along the microdroplet interface that is superheated evaporation;
상기 용매는 증류수 단일 용매, 또는 증류수 및 휘발성 유기용매가 혼합된 2성분 용매이고,The solvent is a distilled water single solvent or a two-component solvent mixed with distilled water and a volatile organic solvent,
상기 환원된 산화그래핀(RGO) 콜로이드 용액의 농도는 0.1~1.0 mg/mL이며,The concentration of the reduced graphene oxide (RGO) colloidal solution is 0.1 ~ 1.0 mg / mL,
상기 기판은 220~350℃의 온도로 가열 및 유지되는 것이고,The substrate is heated and maintained at a temperature of 220 ~ 350 ℃,
상기 스프레이 분사는 1회, 또는 복수회 주기적으로 반복되는 것이며,The spray spray is repeated one time or a plurality of times,
상기 기판의 온도는 PID 컨트롤러(Proportional-Integral-Derivative controller)에 의해 조절되어 상기 스프레이 분사 및 액적의 증발에 따라 그 온도가 하강한 경우 설정된 온도로 다시 회복되는 것이고,The temperature of the substrate is controlled by a Proportional-Integral-Derivative controller (PID) controller to recover the temperature back to the set temperature when the temperature drops as the spray jet and the droplet evaporate.
상기 자가조립(Self-assembly)된 환원된 산화그래핀(RGO) 입자들은 미세기공을 갖는 폼 형상(Foam-like)의 3차원 구조를 형성하는 것을 특징으로 하는,The self-assembly reduced graphene oxide (RGO) particles are characterized in that to form a foam-like (foam-like) three-dimensional structure having micropores,
스프레이 분사를 이용한 3차원 그래핀 구조체의 합성방법을 제공한다(도 1 참조).It provides a method for synthesizing a three-dimensional graphene structure using a spray injection (see Figure 1).
상기 a) 단계는 3차원 그래핀 구조체를 합성하기 위한 전구체로서 환원된 산화그래핀(Reduced Graphene Oxide; RGO)이 용매에 균일하게 분산된 RGO 콜로이드 용액을 준비하는 단계이다.Step a) is a step of preparing an RGO colloid solution in which reduced graphene oxide (RGO) is uniformly dispersed in a solvent as a precursor for synthesizing a three-dimensional graphene structure.
본 단계에서, 상기 환원된 산화그래핀(RGO)은 당분야의 통상적인 방법에 따라 제조 및 구비할 수 있다. 예를 들어, 그래파이트 분말(예컨대, 분말 크기: < 20 μm; 0.5~1.0 μm)을 이용하여 수정된 Hummers법에 따라 그래파이트로부터 산화그래핀(GO)을 제조한 후, 제조된 GO에 N2H4, NaOH 또는 NaBH4와 같은 환원제를 가한 뒤, 60~100℃로 2~6시간 동안 가열하여 환원시킴으로써 RGO를 합성할 수 있다.In this step, the reduced graphene oxide (RGO) may be prepared and provided according to conventional methods in the art. For example, a graphite powder (e.g., powder size: <20 μm; 0.5 ~ 1.0 μm) were prepared for graphene oxide (GO) from the graphite according to the Hummers method modified by using, in the manufacture GO N 2 H RGO can be synthesized by adding a reducing agent such as 4 , NaOH or NaBH 4, and then heating to 60-100 ° C. for 2-6 hours to reduce.
상기 용매는 RGO를 충분히 분산시킬 수 있고, 가열된 기판에 의해 쉽게 증발될 수 있는 종류의 것을 특별한 제한없이 채택하여 사용할 수 있다. 바람직하게는, 증류수를 단독으로 사용하거나, 증류수에 휘발성 유기용매를 혼합한 2성분 용매 시스템을 사용한다.The solvent may be used without particular limitation, a kind that can sufficiently disperse the RGO, and can be easily evaporated by the heated substrate. Preferably, distilled water is used alone, or a two-component solvent system in which a volatile organic solvent is mixed with distilled water is used.
또한, RGO를 용매에 균일하게 분산시키기 위해 초음파 처리 등 당분야의 일반적인 분산방법을 추가적으로 수행할 수 있다.In addition, in order to uniformly disperse the RGO in a solvent, a general dispersing method in the art such as ultrasonication may be additionally performed.
상기 b) 단계는 상기 a) 단계에서 준비된 RGO 콜로이드 용액을 스프레이 노즐을 구비한 소정의 장치(도 2 참조)를 이용하여 마이크로 액적(독립액적)의 형태로 가열된 기판 표면 위에 스프레이 분사하는 단계이다.Step b) is spray spraying the RGO colloidal solution prepared in step a) onto a heated substrate surface in the form of micro droplets (independent droplets) using a predetermined apparatus (see FIG. 2) equipped with a spray nozzle. .
이러한 스프레이 분사에 의해 가열된 기판과 접촉한 마이크로 액적은 기판 표면에서 용매가 순간적으로 증발(더욱 상세하게는, 과열증발) 및 액적 내의 RGO 입자가 순간적으로 응축하게 되고, 이 과정에서 마이크로 액적의 과열증발에 따라 계면에 존재하던 RGO 입자들이 자가조립(Self-assembly)되어 폼 형상의 3차원 그래핀 구조체(도 4 참조)를 형성한다.The microdroplets that come into contact with the heated substrate by this spray spray cause instantaneous evaporation of the solvent on the substrate surface (more specifically, overheating) and instantaneous condensation of RGO particles in the droplets, during which the microdroplets are overheated. As the evaporation, the RGO particles existing at the interface are self-assembly to form a foam-shaped three-dimensional graphene structure (see FIG. 4).
[규칙 제91조에 의한 정정 09.11.2016]　
즉, 본 발명은 커피 또는 소금물 등이 증발하고 난 뒤 표면에 커피 가루와 소금 결정들이 남는 것처럼(도 10 참조), RGO 입자들이 과열증발하는 마이크로 액적 계면을 따라 자가조립되는 원리를 이용한 것이다.[Correction under Article 91 of the Rule 09.11.2016]
That is, the present invention uses the principle that the RGO particles are self-assembled along the interface of the microdroplets overheating, as the coffee powder and salt crystals remain on the surface after the evaporation of coffee or brine (see FIG. 10).
[규칙 제91조에 의한 정정 09.11.2016]　
[Correction under Article 91 of the Rule 09.11.2016]
[규칙 제91조에 의한 정정 09.11.2016]　
[Correction under Article 91 of the Rule 09.11.2016]
상기 RGO 용액의 스프레이 분사는 1회, 또는 복수회 주기적으로 반복 수행되는 것이다.The spray injection of the RGO solution is repeated one or more times.
이때, 주기적인 스프레이 분사의 경우 "마이크로 액적의 증발 - 기판의 표면 온도 하강 및 회복 - 스프레이 분사"를 1 주기로 한 프로세스가 반복되면서 3차원 그래핀 구조체 필름을 형성한다. 이러한 주기적인 스프레이 분사는 소정의 자동분사 장치(도 3 참조)를 통해 수행될 수 있다.At this time, in the case of the periodic spray spraying, the process of "Evaporation of micro droplets-surface temperature drop and recovery of the substrate-spray spraying" in one cycle is repeated to form a three-dimensional graphene structure film. This periodic spray injection can be carried out through any automatic spray device (see FIG. 3).
본 발명에서는, RGO 용액의 분사회수(총 분사량)를 조절하여 기판 위의 코팅 두께를 조절할 수 있다. 구체적으로, 분사회수가 증가함에 따라 코팅 두께는 증가하고, 기공 크기는 상대적으로 감소함을 실험을 통해 확인하였다.In the present invention, the coating thickness on the substrate can be controlled by adjusting the number of powders (total injection amount) of the RGO solution. Specifically, it was confirmed through experiments that the coating thickness increases and the pore size decreases as the number of powders increases.
일 구체예에서, 상기 스프레이 분사는 0.1 mg/mL 농도의 RGO 용액을 1회당 분사량 30 mL씩 2회 반복(총 60 mL) 수행하는 것일 수 있다.In one embodiment, the spray spraying may be performed by repeating the RGO solution at a concentration of 0.1 mg / mL twice (30 mL in total), each 30 mL of injection amount.
본 단계에서, 상기 기판은 가열되어 220~350℃(바람직하게는, 250℃)의 온도로 유지되는 것이다. 기판 표면의 온도가 220℃ 미만이면 스프레이 분사된 마이크로 액적의 과열증발이 원활히 이루어지지 않을 수 있으며, 350℃를 초과하면 코팅량이 크게 감소하는 문제가 발생할 수 있다.In this step, the substrate is heated to be maintained at a temperature of 220 ~ 350 ℃ (preferably, 250 ℃). If the temperature of the substrate surface is less than 220 ℃ may not be a smooth overheating of the spray-injected micro droplets, if it exceeds 350 ℃ may cause a problem that the coating amount is greatly reduced.
또한, 상기 기판의 온도는 PID 컨트롤러(Proportional-Integral-Derivative controller)에 의해 조절되는 것으로서, 구체적으로 상기 스프레이 분사 및 액적의 증발에 따라 기판 표면의 온도가 하강한 경우 PID 컨트롤러의 제어에 따라 기판 표면의 온도가 기설정된 온도(220~350℃)로 자동 회복되도록 구성된다.In addition, the temperature of the substrate is controlled by a Proportional-Integral-Derivative controller (PID controller). Specifically, when the temperature of the substrate surface decreases according to the spray injection and the evaporation of droplets, the substrate surface is controlled by the PID controller. The temperature of is configured to automatically recover to a predetermined temperature (220 ~ 350 ℃).
RGO 용액을 스프레이 분사하는 방법은 특별히 제한되지 않으며, 용액을 초음파(노즐) 분무 장치 등에 투입하여 액적의 형태로 기판 상에 분사하면 된다. 초음파(노즐) 분무 장치는 초음파 진동을 통해 RGO 용액으로부터 균일한 크기 분포를 지니는 마이크로미터 단위의 액적을 자유롭게 형성할 수 있으며, 이러한 구형 액적 내부에는 RGO가 용매 내에 균일하게 분산되어 있는 형태로 존재한다.The method of spray-injecting an RGO solution is not specifically limited, What is necessary is just to inject | pour a solution into an ultrasonic (nozzle) spray apparatus etc., and to spray on a board | substrate in the form of a droplet. Ultrasonic (nozzle) spraying apparatus can freely form micrometer-scale droplets having a uniform size distribution from the RGO solution through ultrasonic vibration, in which the RGO is uniformly dispersed in the solvent. .
일 구체예에서, 상기 마이크로 독립액적의 크기는 스프레이 노즐을 통해 평균 10 μm로 조절되는 것일 수 있다(도 1 참조). 즉, 액적의 크기는 기판 상에서 최종 얻어지는 RGO 입자보다 상대적으로 큰 크기를 갖도록 조절되는 것이 바람직한바, 이는 액적에 포함된 용매가 증발하면서 액적에 포함된 RGO 입자들만 남아 자가조립되어 원래 액적의 크기보다 작은 크기의 RGO 입자들이 구조체로 형성되기 때문이다.In one embodiment, the size of the micro independent droplets may be adjusted to an average of 10 μm through a spray nozzle (see FIG. 1). That is, the size of the droplets is preferably adjusted to have a relatively larger size than the final RGO particles obtained on the substrate, as the solvent contained in the droplets evaporate only the RGO particles contained in the droplets remain self-assembly than the size of the original droplets This is because small sized RGO particles are formed into a structure.
상기 RGO 용액의 농도는 0.1~1.0 mg/mL가 적절하다. 그 농도가 0.1 mg/mL 미만이면 RGO의 양이 너무 적어 소망하는 크기 내지 두께의 3차원 그래핀 구조체를 원활하게 형성하기 어려워질 수 있으며, 1.0 mg/mL를 초과하여 RGO의 양이 너무 많으면 얻어지는 구조체의 기공 크기가 상대적으로 커져서 미세기공 활성화에 따른 비표면적 증가의 효과를 구현하기 어려워질 수 있다.The concentration of the RGO solution is appropriate 0.1 ~ 1.0 mg / mL. If the concentration is less than 0.1 mg / mL, the amount of RGO may be too small, making it difficult to form a three-dimensional graphene structure of a desired size to thickness smoothly. If the amount of RGO is excessively greater than 1.0 mg / mL, As the pore size of the structure becomes relatively large, it may be difficult to realize the effect of the specific surface area increase due to the activation of the micropores.
일 구체예에서, 용매로 증류수 단일 용매를 사용할 경우, 상기 RGO 용액의 농도는 0.1 mg/mL로 조절하는 것이 미세기공 극대화 측면에서 바람직하다.In one embodiment, when using a single solvent of distilled water as the solvent, it is preferable to adjust the concentration of the RGO solution to 0.1 mg / mL in terms of maximizing micropores.
상기 용매로는 증류수를 단독으로 사용할 수도 있으나, 경우에 따라서는 증류수 및 휘발성 유기용매가 혼합된 2성분 용매(Binary mixture)를 사용하고 그 몰분율(Mole fraction)을 조절함으로써, 3차원 그래핀 구조체의 구체적인 적용 분야에 맞도록 기공 특성을 제어할 수 있다. As the solvent, distilled water may be used alone, but in some cases, by using a binary mixture in which distilled water and a volatile organic solvent are mixed and adjusting the mole fraction thereof, Pore properties can be controlled to suit specific applications.
이때, 상기 휘발성 유기용매로는 알코올계 유기용매, 예컨대 메탄올(Methanol) 또는 에탄올(Ethanol)을 사용할 수 있다.In this case, the volatile organic solvent may be an alcohol-based organic solvent, such as methanol (Methanol) or ethanol (Ethanol).
일 구체예에서, RGO 용액 중 상기 휘발성 유기용매의 몰분율은 0.05~0.7일 수 있으며, 증류수 베이스의 RGO 용액에서 휘발성 유기용매의 몰분율이 증가함에 따라 기공 크기가 감소하여 몰분율 0.2 이상부터는 나노포러스(Nanoporous) 구조의 3차원 그래핀 구조체가 형성됨이 실험을 통해 확인되었다.In one embodiment, the mole fraction of the volatile organic solvent in the RGO solution may be 0.05 ~ 0.7, the pore size decreases as the mole fraction of the volatile organic solvent in the RGO solution of distilled water is increased, the nanoporous (Nanoporous from 0.2 or more mole fraction) Experimentally confirmed that the three-dimensional graphene structure of the structure) is formed.
RGO 용액이 스프레이 분사되는 상기 기판의 종류는 특별히 제한되지 않으며, 예를 들어 실리콘(Si) 기판, 유리 기판 또는 고분자 기판 등을 사용할 수 있다. 바람직하게는, 실리콘(Si) 기판을 사용할 수 있다.The kind of the substrate on which the RGO solution is spray sprayed is not particularly limited, and for example, a silicon (Si) substrate, a glass substrate or a polymer substrate may be used. Preferably, a silicon (Si) substrate can be used.
본 발명에서는 RGO 용액의 농도, 기판 온도, 분사회수, 용매의 종류 및 혼합비를 주요 조절 변수로 하되, 필요에 따라 분사 높이(기판과 노즐간의 거리), 분사 압력 및 분출 구멍의 크기(Orifice size) 등을 추가적으로 적절히 조절할 수 있다.In the present invention, the concentration of the RGO solution, the substrate temperature, the number of spin-offs, the type of solvent and the mixing ratio are the main control variables, but the injection height (distance between the substrate and the nozzle), the injection pressure, and the size of the ejection hole (Orifice size) as necessary. Etc. can be further suitably adjusted.
본 발명에 따라 자가조립(Self-assembly)된 RGO 입자들은 미세기공을 갖는 폼 형상(Foam-like)의 3차원 구조를 형성하며, 이때 상기 미세기공의 크기는 0.1~10 μm 수준, 평균 크기는 수 μm 이하인 것일 수 있다.Self-assembled RGO particles according to the present invention form a foam-like (foam-like) three-dimensional structure having micropores, wherein the size of the micropores is 0.1 ~ 10 μm level, the average size is It may be several μm or less.
본 발명에 따라 합성된 3차원 그래핀 구조체는 에너지 저장 소자, 열전달 장치 또는 탈염 장치 등 다양한 분야의 소재로 활용될 수 있다.The three-dimensional graphene structure synthesized according to the present invention may be used as a material in various fields such as an energy storage device, a heat transfer device, or a desalination device.
상기 에너지 저장 소자로는 커패시터, 각종 배터리(예컨대, 2차전지, 태양전지), 연료전지 등을 들 수 있다. 본 발명에 따라 합성된 3차원 그래핀 구조체는 차세대 에너지 저장 분야에 직접적인 적용이 가능하며, 그래핀의 우수한 전기전도도와 더불어 이를 3차원으로 합성하여 비표면적을 극대화한 것인바, 높은 에너지 밀도와 출력 밀도가 동시에 요구되는 슈퍼커패시터(Supercapacitor)의 전극 소재로서 매우 이상적으로 사용될 수 있다. 아울러, 본 발명에 따라 합성된 3차원 그래핀 구조체를 레독스 흐름 전지(Redox Flow Battery; RFB)에 사용할 경우, 그래핀 조각 표면에 형성된 산화 작용기를 촉매로 작용하여 충방전 속도를 증진시킬 수 있다.The energy storage element may include a capacitor, various batteries (eg, secondary cells, solar cells), fuel cells, and the like. The three-dimensional graphene structure synthesized according to the present invention can be directly applied to the next-generation energy storage field, and by maximizing the specific surface area by synthesizing it in three dimensions with excellent electrical conductivity of graphene, high energy density and output power It can be used very ideally as an electrode material of supercapacitors where density is required at the same time. In addition, when the three-dimensional graphene structure synthesized according to the present invention is used in a Redox Flow Battery (RFB), an oxidation functional group formed on the surface of the graphene fragment may act as a catalyst to increase charge and discharge rates. .
또한, 본 발명에 따라 합성된 3차원 그래핀 구조체는 그래핀의 높은 열전도도 특성(문헌치: 5000W/mK, 구리: 400W/mK)에 의해 열에너지의 관리가 핵심인 원자력 발전 및 화력 발전 분야 등의 열전달 소재로 활용될 수 있다. 아울러, 그래핀의 열확산 능력과 3차원 구조의 물 흡수 능력으로 인해 비등 성능의 한계치인 임계열유속을 증진시킬 수 있는 장점이 있다.In addition, the three-dimensional graphene structure synthesized according to the present invention is a nuclear power and thermal power generation field where the management of thermal energy is the core by the high thermal conductivity characteristics of the graphene (document value: 5000W / mK, copper: 400W / mK) It can be used as a heat transfer material of. In addition, due to the heat diffusion ability of the graphene and the water absorption ability of the three-dimensional structure there is an advantage that can improve the critical heat flux, the limit of boiling performance.
또한, 본 발명에 따라 합성된 3차원 그래핀 구조체는 축전식 탈염(Capacitive deionization; CDI) 공정의 전극으로 사용될 수 있으며, 이 경우 타겟 이온만 선택적으로 제거하여 탈염 효율을 극대화하고, 전력비를 절감하며, 장기간 전극을 사용할 수 있는 장점이 있다.In addition, the three-dimensional graphene structure synthesized according to the present invention can be used as an electrode of the capacitive deionization (CDI) process, in this case by selectively removing only the target ions to maximize the desalination efficiency, reducing the power cost This has the advantage that the electrode can be used for a long time.
그 외, 본 발명에 따라 합성된 3차원 그래핀 구조체는 촉매 용도, 광학 소재, 바이오 소재, 태양열 소재 등에도 광범위하게 적용이 가능할 것이다.In addition, the three-dimensional graphene structure synthesized according to the present invention will be widely applicable to catalyst applications, optical materials, biomaterials, solar materials, and the like.
본 발명은 RGO 용액을 타겟 표면에 직접 스프레이 분사하는바, 폴리머, 금속 등의 골격체(Framework)나 식각 등의 추가적인 공정 없이 간편하고 용이한 방법으로 3차원 그래핀 구조체를 대량생산할 수 있다.The present invention spray sprays the RGO solution directly onto the target surface, so that the 3D graphene structure can be mass-produced in a simple and easy manner without additional processes such as a framework or etching such as polymer or metal.
또한, 본 발명은 스프레이 분사에 의한 그래핀 구조체 형성과 관련된 제반 공정변수를 조절하여, 차세대 에너지 저장 소자(특히, 슈퍼커패시터), 열전달 장치 및 탈염 장치 등 다양한 분야의 소재로 직접 적용이 가능한 최적의 3차원 구조를 형성할 수 있다.In addition, the present invention by controlling the various process parameters associated with the formation of the graphene structure by spray injection, it is possible to apply directly to the material of various fields such as next-generation energy storage device (especially supercapacitor), heat transfer device and desalination device Three-dimensional structure can be formed.
도 1은 본 발명에 따라 마이크로 독립액적 분사를 통해 3차원 그래핀 구조체를 합성하는 방법을 보여주는 모식도이다.1 is a schematic diagram showing a method for synthesizing a three-dimensional graphene structure through micro-independent droplet injection according to the present invention.
도 2는 본 발명에 따른 마이크로 독립액적 분사에 사용되는 장치에 관한 개략도이다.2 is a schematic diagram of an apparatus used for micro independent droplet injection according to the present invention.
도 3은 본 발명에 사용되는 스프레이 자동분사 장치의 일예를 보여주는 사진이다.Figure 3 is a photograph showing an example of the spray automatic injection device used in the present invention.
도 4는 본 발명에 따라 합성된 3차원 그래핀 구조체의 형상을 대표적으로 보여주는 주사전자현미경(Scanning Electron Microscopy; SEM) 이미지이다.4 is a scanning electron microscope (SEM) image representatively showing the shape of the three-dimensional graphene structure synthesized according to the present invention.
도 5 내지 도 9는 본 발명의 실시예들에 따라 RGO 용액 내 그래핀의 농도, 분사회수, 기판 표면 온도 및 용매의 구성을 달리하며 합성된 3차원 그래핀 구조체들의 형상을 보여주는 주사전자현미경(SEM) 이미지이다.5 to 9 are scanning electron microscopes showing the shapes of the synthesized three-dimensional graphene structures with different concentrations of graphene in the RGO solution, spin water, substrate surface temperature and solvent composition according to embodiments of the present invention. SEM) image.
이하, 실시예를 통해 본 발명을 보다 구체적으로 설명한다. 그러나 이들 실시예는 본 발명의 이해를 돕기 위한 것일 뿐 어떠한 의미로든 본 발명의 범위가 이들 실시예로 한정되는 것은 아니다.Hereinafter, the present invention will be described in more detail with reference to Examples. However, these examples are only for the understanding of the present invention, and the scope of the present invention in any sense is not limited to these examples.
실시예 1 내지 8: 3차원 그래핀 구조체의 합성(그래핀 농도 및 분사회수 별)Examples 1 to 8: Synthesis of 3D Graphene Structures (Graphene Concentration and Number of Fractions)
하기 표 1과 같은 조건으로 RGO 콜로이드 용액의 농도, 분사회수(총 분사량), 기판 온도 및 용매를 설정하여,By setting the concentration of the RGO colloidal solution, the number of jet water (total injection amount), the substrate temperature and the solvent under the conditions as shown in Table 1,
도 2와 같은 장치를 통해 RGO 콜로이드 용액을 가열된 기판 표면 위에 액적 형태로 스프레이 분사시켜 3차원 그래핀 구조체를 합성하였다.The RGO colloidal solution was spray-sprayed onto the heated substrate surface in the form of droplets through a device such as FIG. 2 to synthesize a 3D graphene structure.
(* 2회 분사의 경우는, 1차 분사 후 기판의 온도가 하강하였을 때 PID 컨트롤러에 의해 원래 온도로 자동 회복되도록 한 다음 2차 분사를 수행하였다.)(* In the case of 2 injections, when the temperature of the substrate decreases after the 1st injection, the PID controller automatically recovers to the original temperature and then performs the 2nd injection.)
[표 1] 3차원 그래핀 구조체의 합성(그래핀 농도 및 분사회수 별)Table 1 Synthesis of 3D Graphene Structures (by Graphene Concentration and Number of Fractions)
Figure PCTKR2016012002-appb-I000002
Figure PCTKR2016012002-appb-I000002
도 5에서 보듯이, 증류수 base 용액 내 그래핀의 농도가 감소할수록 합성된 3차원 그래핀 구조체의 기공 크기가 감소하고 미세기공 활성도가 증가하였으며, 용액 농도 0.1 mg/mL에서 가장 우수한 기공 특성을 나타내었다. 이는, 3차원 그래핀 구조체 합성을 위한 그래핀 전구체 용액의 농도를 변화시켜 구조체의 기공 크기 및 활성도를 조절할 수 있음을 의미한다.As shown in FIG. 5, as the concentration of graphene in the distilled water base solution decreased, the pore size and micropore activity of the synthesized three-dimensional graphene structure decreased, and the pore size of the solution was 0.1 mg / mL. It was. This means that the pore size and activity of the structure can be controlled by changing the concentration of the graphene precursor solution for synthesizing the three-dimensional graphene structure.
도 6 및 도 7을 보면, 각각의 RGO 용액 농도에 있어서 그래핀 분사량(분사회수)이 증가할수록 코팅 두께가 증가하고 기공 크기가 감소하였음을 알 수 있다. 이는, 스프레이 분사의 주기적 반복이 코팅 두께는 물론 구조체의 기공 특성에도 일부 영향을 미침을 의미한다.6 and 7, it can be seen that the coating thickness increases and the pore size decreases as the graphene injection amount (partition number) increases for each RGO solution concentration. This means that the periodic repetition of the spray spraying has some effect on the coating thickness as well as the pore properties of the structure.
실시예 9 내지 12: 3차원 그래핀 구조체의 합성(기판 온도 별)Examples 9 to 12 synthesis of three-dimensional graphene structure (substrate temperature)
하기 표 2와 같은 조건으로 RGO 콜로이드 용액의 농도, 분사회수(총 분사량), 기판 온도 및 용매를 설정하여,By setting the concentration of the RGO colloidal solution, the number of jet water (total injection amount), the substrate temperature and the solvent under the conditions as shown in Table 2,
도 2와 같은 장치를 통해 RGO 콜로이드 용액을 가열된 기판 표면 위에 액적 형태로 스프레이 분사시켜 3차원 그래핀 구조체를 합성하였다.The RGO colloidal solution was spray-sprayed onto the heated substrate surface in the form of droplets through a device such as FIG. 2 to synthesize a 3D graphene structure.
[표 2] 3차원 그래핀 구조체의 합성(기판 온도 별)[Table 2] Synthesis of 3D Graphene Structure by Substrate Temperature
Figure PCTKR2016012002-appb-I000003
Figure PCTKR2016012002-appb-I000003
도 8에서 보듯이, 기판의 표면 온도가 증가할수록 코팅량이 현저히 감소하였으며, 기판 온도 250℃에서 최적의 3차원 구조를 형성하였다. 이는, 과열증발이 일어나는 기판의 표면 온도가 3차원 그래핀 구조체의 모폴로지에 영향을 미침을 의미한다.As shown in FIG. 8, as the surface temperature of the substrate increases, the coating amount significantly decreased, and an optimal three-dimensional structure was formed at the substrate temperature of 250 ° C. This means that the surface temperature of the substrate where superheat evaporation affects the morphology of the three-dimensional graphene structure.
* 실시예 13 내지 18: 3차원 그래핀 구조체의 합성(용매의 구성 및 몰분율 별) Examples 13 to 18: Synthesis of three-dimensional graphene structure (by solvent composition and mole fraction)
하기 표 3과 같은 조건으로 RGO 콜로이드 용액의 농도, 분사회수(총 분사량), 기판 온도 및 용매를 설정하여,To set the concentration of RGO colloidal solution, the number of jet water (total injection amount), the substrate temperature and the solvent under the conditions as shown in Table 3,
도 2와 같은 장치를 통해 RGO 콜로이드 용액을 가열된 기판 표면 위에 액적 형태로 스프레이 분사시켜 3차원 그래핀 구조체를 합성하였다.The RGO colloidal solution was spray-sprayed onto the heated substrate surface in the form of droplets through a device such as FIG. 2 to synthesize a 3D graphene structure.
[표 3] 3차원 그래핀 구조체의 합성(용매의 구성 및 몰분율 별)Table 3 Synthesis of 3D Graphene Structures (by Solvent Composition and Mole Fraction)
Figure PCTKR2016012002-appb-I000004
Figure PCTKR2016012002-appb-I000004
도 9를 보면, 증류수 base RGO 용액에 휘발성 유기용매를 첨가한 경우 증류수 단독 용매를 사용한 경우와는 다른 기공 특성을 보이고, 첨가된 휘발성 유기용매의 몰분율이 증가함에 따라 기공 크기가 감소하며, 몰분율 0.2 이상부터는 필름 두께가 얇아지면서 구조체의 기공 구조가 나노포러스(Nanoporous) 구조로 전이됨을 알 수 있다. 이는, 첨가하는 휘발성 유기용매의 종류 및 몰분율을 변화시켜 3차원 그래핀 구조체가 적용되는 소자의 요구 특성에 맞도록 기공 특성을 적절히 조절할 수 있음을 의미한다.9, when the volatile organic solvent is added to the distilled water base RGO solution, the pore characteristics are different from those of using the distilled water alone solvent, the pore size decreases as the mole fraction of the added volatile organic solvent increases, and the mole fraction is 0.2. From the above, it can be seen that as the film thickness becomes thin, the pore structure of the structure is transferred to a nanoporous structure. This means that by changing the type and mole fraction of the volatile organic solvent to be added, it is possible to properly adjust the pore characteristics to meet the required characteristics of the device to which the three-dimensional graphene structure is applied.
3차원 그래핀 구조체는 슈퍼커패시터와 같은 차세대 에너지 저장 분야의 핵심 소재로서 그 자체가 고부가가치 산업일 뿐만 아니라, 고밀도 에너지원이 요구되는 국가의 차세대 기간 산업(신재생에너지 발전 및 수소·전기자동차 분야)와도 밀접한 연관성을 지닌다.The three-dimensional graphene structure is a key material in the next generation energy storage field such as supercapacitors, and is not only a high value-added industry itself, but also a next-generation infrastructure industry in the country where high-density energy sources are required (renewable energy generation and hydrogen and electric vehicle fields). It is also closely related to).
본 발명은 간단하고 용이한 방식으로 고품질의 3차원 그래핀 구조체를 대량생산할 수 있는 방법으로서, 차세대 에너지 저장 소자, 열전달 장치, 발전 장치 및 탈염 장치 등 다양한 장치의 성능 개선을 위한 소재로서 광범위하게 적용이 가능할 것이다.The present invention is a method for mass production of high-quality three-dimensional graphene structure in a simple and easy manner, widely applied as a material for improving the performance of various devices such as next-generation energy storage devices, heat transfer devices, power generation devices and desalination devices. This will be possible.

Claims (14)

  1. a) 환원된 산화그래핀(Reduced Graphene Oxide; RGO)을 용매에 분산시켜 환원된 산화그래핀(RGO) 콜로이드 용액을 준비하는 단계; 및a) preparing a reduced graphene oxide (RGO) colloidal solution by dispersing reduced graphene oxide (RGO) in a solvent; And
    b) 상기 환원된 산화그래핀(RGO) 콜로이드 용액을 스프레이 노즐을 통해 마이크로 독립액적의 형태로 가열된 기판 표면 위에 스프레이 분사시켜, 환원된 산화그래핀(RGO) 입자들이 과열증발(Superheated evaporation)하는 마이크로 액적 계면을 따라 자가조립(Self-assembly)되도록 하는 단계;를 포함하며,b) spraying the reduced graphene oxide (RGO) colloidal solution on the surface of the heated substrate in the form of microindependent droplets through a spray nozzle, whereby the reduced graphene oxide (RGO) particles are superheated evaporation; Including self-assembly along the microdroplet interface;
    상기 용매는 증류수 단일 용매, 또는 증류수 및 휘발성 유기용매가 혼합된 2성분 용매이고,The solvent is a distilled water single solvent or a two-component solvent mixed with distilled water and a volatile organic solvent,
    상기 환원된 산화그래핀(RGO) 콜로이드 용액의 농도는 0.1~1.0 mg/mL이며,The concentration of the reduced graphene oxide (RGO) colloidal solution is 0.1 ~ 1.0 mg / mL,
    상기 기판은 220~350℃의 온도로 가열 및 유지되는 것이고,The substrate is heated and maintained at a temperature of 220 ~ 350 ℃,
    상기 스프레이 분사는 1회, 또는 복수회 주기적으로 반복되는 것이며,The spray spray is repeated one time or a plurality of times,
    상기 기판의 온도는 PID 컨트롤러(Proportional-Integral-Derivative controller)에 의해 조절되어 상기 스프레이 분사 및 액적의 증발에 따라 그 온도가 하강한 경우 설정된 온도로 다시 회복되는 것이고,The temperature of the substrate is controlled by a Proportional-Integral-Derivative controller (PID) controller to recover the temperature back to the set temperature when the temperature drops as the spray jet and the droplet evaporate.
    상기 자가조립(Self-assembly)된 환원된 산화그래핀(RGO) 입자들은 미세기공을 갖는 폼 형상(Foam-like)의 3차원 구조를 형성하는 것을 특징으로 하는,The self-assembly reduced graphene oxide (RGO) particles are characterized in that to form a foam-like (foam-like) three-dimensional structure having micropores,
    스프레이 분사를 이용한 3차원 그래핀 구조체의 합성방법.Synthesis method of 3D graphene structure using spray injection.
  2. 제1항에 있어서,The method of claim 1,
    상기 용매는 증류수 단일 용매이고, 상기 환원된 산화그래핀(RGO) 콜로이드 용액의 농도는 0.1 mg/mL인 것을 특징으로 하는, 스프레이 분사를 이용한 3차원 그래핀 구조체의 합성방법.The solvent is a distilled water single solvent, the concentration of the reduced graphene oxide (RGO) colloidal solution, characterized in that 0.1 mg / mL, method of synthesizing a three-dimensional graphene structure using a spray.
  3. 제2항에 있어서,The method of claim 2,
    상기 스프레이 분사는 1회당 분사량 30 mL씩 2회 반복 수행되는 것을 특징으로 하는, 스프레이 분사를 이용한 3차원 그래핀 구조체의 합성방법.The spray injection is a method of synthesizing a three-dimensional graphene structure using a spray injection, characterized in that it is repeatedly performed twice by 30 mL per injection amount.
  4. 제3항에 있어서,The method of claim 3,
    상기 기판의 온도는 250℃인 것을 특징으로 하는, 스프레이 분사를 이용한 3차원 그래핀 구조체의 합성방법.The substrate is a temperature of 250 ℃, characterized in that the synthesis method of the three-dimensional graphene structure using a spray.
  5. 제1항에 있어서,The method of claim 1,
    상기 용매는 증류수 및 알코올계 유기용매가 혼합된 2성분 용매인 것을 특징으로 하는, 스프레이 분사를 이용한 3차원 그래핀 구조체의 합성방법.The solvent is a method of synthesizing a three-dimensional graphene structure using a spray, characterized in that the distilled water and the alcohol-based organic solvent mixed two-component solvent.
  6. 제5항에 있어서,The method of claim 5,
    상기 알코올계 유기용매는 메탄올 또는 에탄올인 것을 특징으로 하는, 스프레이 분사를 이용한 3차원 그래핀 구조체의 합성방법.The alcohol-based organic solvent is characterized in that methanol or ethanol, method of synthesizing a three-dimensional graphene structure using a spray injection.
  7. 제6항에 있어서,The method of claim 6,
    상기 환원된 산화그래핀(RGO) 콜로이드 용액 중 알코올계 유기용매의 몰분율(Mole fraction)은 0.05~0.7인 것을 특징으로 하는, 스프레이 분사를 이용한 3차원 그래핀 구조체의 합성방법.Mole fraction (mole fraction) of the alcohol-based organic solvent in the reduced graphene oxide (RGO) colloidal solution, characterized in that 0.05 to 0.7, the synthesis method of the three-dimensional graphene structure using a spray.
  8. 제7항에 있어서,The method of claim 7, wherein
    상기 환원된 산화그래핀(RGO) 콜로이드 용액 중 알코올계 유기용매의 몰분율(Mole fraction)은 0.2~0.7이며, 상기 3차원 그래핀 구조체는 나노포러스(Nanoporous) 구조를 갖는 것을 특징으로 하는, 스프레이 분사를 이용한 3차원 그래핀 구조체의 합성방법.Mole fraction (mole fraction) of the alcohol-based organic solvent in the reduced graphene oxide (RGO) colloidal solution is 0.2 ~ 0.7, the three-dimensional graphene structure, characterized in that having a nanoporous (Nanoporous) structure, spray injection 3D graphene structure synthesis method using.
  9. 제1항에 있어서,The method of claim 1,
    상기 기판은 실리콘(Si) 기판인 것을 특징으로 하는, 스프레이 분사를 이용한 3차원 그래핀 구조체의 합성방법.The substrate is a silicon (Si) substrate, characterized in that the synthesis of three-dimensional graphene structure using a spray injection.
  10. 제1항에 있어서,The method of claim 1,
    상기 스프레이 노즐을 통해 마이크로 독립액적의 크기가 10 μm로 조절된 후 분사되는 것을 특징으로 하는, 스프레이 분사를 이용한 3차원 그래핀 구조체의 합성방법.Method of synthesizing a three-dimensional graphene structure using a spray spray, characterized in that the spray is controlled after the size of the micro-independent droplet is adjusted to 10 μm through the spray nozzle.
  11. 제1항에 있어서,The method of claim 1,
    상기 3차원 그래핀 구조체의 미세기공의 크기는 0.1~10 μm인 것을 특징으로 하는, 스프레이 분사를 이용한 3차원 그래핀 구조체의 합성방법.The size of the micropores of the three-dimensional graphene structure is characterized in that 0.1 ~ 10 μm, 3D graphene structure synthesis method using a spray injection.
  12. 제1항 내지 제11항 중 어느 한 항에 있어서,The method according to any one of claims 1 to 11,
    상기 3차원 그래핀 구조체는 에너지 저장 소자, 열전달 장치 또는 탈염 장치에 사용되는 것을 특징으로 하는, 스프레이 분사를 이용한 3차원 그래핀 구조체의 합성방법.The three-dimensional graphene structure is characterized in that used in the energy storage device, heat transfer device or desalting device, method of synthesizing a three-dimensional graphene structure using a spray injection.
  13. 제12항에 있어서,The method of claim 12,
    상기 3차원 그래핀 구조체는 커패시터, 배터리, 연료전지, 레독스 흐름 전지(Redox Flow Battery; RFB) 또는 축전식 탈염(Capacitive deionization; CDI) 장치에 사용되는 것을 특징으로 하는, 스프레이 분사를 이용한 3차원 그래핀 구조체의 합성방법.The three-dimensional graphene structure is used in a capacitor, a battery, a fuel cell, a redox flow battery (RFB) or capacitive deionization (CDI) device, characterized in that the three-dimensional spray spray Synthesis method of graphene structure.
  14. 제13항에 있어서,The method of claim 13,
    상기 3차원 그래핀 구조체는 슈퍼커패시터(Supercapacitor)의 전극 소재로 사용되는 것을 특징으로 하는, 스프레이 분사를 이용한 3차원 그래핀 구조체의 합성방법.The three-dimensional graphene structure is characterized in that used as the electrode material of the supercapacitor (Supercapacitor), the synthesis method of the three-dimensional graphene structure using a spray injection.
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