KR100798131B1 - Coating Method of titanium dioxide of a lower order on Carbon Nanotube - Google Patents
Coating Method of titanium dioxide of a lower order on Carbon Nanotube Download PDFInfo
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- KR100798131B1 KR100798131B1 KR1020060065119A KR20060065119A KR100798131B1 KR 100798131 B1 KR100798131 B1 KR 100798131B1 KR 1020060065119 A KR1020060065119 A KR 1020060065119A KR 20060065119 A KR20060065119 A KR 20060065119A KR 100798131 B1 KR100798131 B1 KR 100798131B1
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
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- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
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Abstract
본 발명은 탄소나노튜브 표면에 저차산화티타늄을 코팅하는 방법에 관한 것으로서, 더욱 상세하게는 습식환원법을 이용하여 탄소나노튜브 표면에서 저차산화티타늄 나노입자의 핵 생성과 동시에 성장을 유도하여 탄소나노튜브 표면에 균일하게 코팅하여, 전기전도도, 내화성 및 내구성이 우수하여 전계방출 소재용으로 적용이 용이한 탄소나노튜브 표면에 저차산화티타늄을 코팅하는 방법에 관한 것이다. The present invention relates to a method of coating low-titanium oxide on the surface of carbon nanotubes, and more particularly, by using a wet reduction method to induce the growth and nucleation of low-titanium oxide nanoparticles on the surface of carbon nanotubes carbon nanotubes The present invention relates to a method of coating low-titanium oxide on the surface of carbon nanotubes, which are uniformly coated on the surface, and excellent in electrical conductivity, fire resistance, and durability, and are easy to apply for field emission materials.
저차산화티타늄 나노입자 코팅, 탄소나노튜브, 용액환원법 Low Titanium Oxide Nanoparticle Coating, Carbon Nanotube, Solution Reduction Method
Description
도 1은 본 발명의 실시예 1에서 제조된 저차산화티타늄 나노입자의 투과전자현미경(TEM) 사진이다.1 is a transmission electron microscope (TEM) photograph of low-order titanium oxide nanoparticles prepared in Example 1 of the present invention.
도 2는 본 발명의 실시예 1에서 제조된 저차산화티타늄 나노입자가 균일하게 코팅된 탄소나노튜브의 투과전자현미경(TEM) 사진이다.2 is a transmission electron microscope (TEM) photograph of carbon nanotubes uniformly coated with low-titanium oxide nanoparticles prepared in Example 1 of the present invention.
도 3은 본 발명의 실시예 1에서 제조된 저차산화티타늄 나노입자의 X-선 회절분석을 나타낸 것이다.Figure 3 shows the X-ray diffraction analysis of the low titanium oxide nanoparticles prepared in Example 1 of the present invention.
본 발명은 탄소나노튜브 표면에 저차산화티타늄을 코팅하는 방법에 관한 것으로서, 더욱 상세하게는 습식환원법을 이용하여 탄소나노튜브 표면에서 저차산화티타늄 나노입자의 핵 생성과 동시에 성장을 유도하여 탄소나노튜브 표면에 균일하게 코팅하여, 전기전도도, 내화성 및 내구성이 우수하여 전계방출 소재용으로 적용 이 용이한 탄소나노튜브 표면에 저차산화티타늄을 코팅하는 방법에 관한 것이다. The present invention relates to a method of coating low-titanium oxide on the surface of carbon nanotubes, and more particularly, by using a wet reduction method to induce the growth and nucleation of low-titanium oxide nanoparticles on the surface of carbon nanotubes carbon nanotubes The present invention relates to a method of coating low-titanium oxide on the surface of carbon nanotubes that are easily applied for field emission materials due to uniform coating on the surface and excellent electric conductivity, fire resistance and durability.
탄소나노튜브의 표면에 나노입자를 코팅하는 종래의 방법은 주로 기상법에 의한 것으로, 전자빔 등을 이용하여 코팅하고자 하는 물질을 기화시켜 탄소나노튜브의 표면에 응축시킴으로써 원하는 나노입자를 코팅하는 방법[Applied Physics Letters, Vol.77, No. 19, p3015 (2000), Chemical Physics Letters, 331, p35 (2000)]으로, Pd, Au, Fe, Al, Pb, Ni 등과 같은 금속 나노입자의 코팅에 사용된다. 그러나, 이러한 방법은 많은 부피의 탄소나노튜브에 코팅할 경우 기체상과 쉽게 접촉하는 표면 부분과 기체의 확산이 어려운 내부의 코팅이 서로 불균일해질 수 있다는 문제가 있기 때문에 대량 생산이 곤란하다.The conventional method of coating nanoparticles on the surface of carbon nanotubes is mainly by vapor phase method, and the method of coating desired nanoparticles by vaporizing a material to be coated using an electron beam or the like and condensing on the surface of carbon nanotubes. Physics Letters, Vol. 77, No. 19, p3015 (2000), Chemical Physics Letters, 331, p35 (2000), are used for the coating of metal nanoparticles such as Pd, Au, Fe, Al, Pb, Ni and the like. However, this method is difficult to mass-produce when coating a large volume of carbon nanotubes because there is a problem that the surface portion easily contacting the gas phase and the internal coating which is difficult to diffuse the gas may be uneven with each other.
이에 기상코팅법의 단점을 극복하기 위하여 습식 코팅법에 의하여 Au, Pd, Pt등의 금속과, SnO2, Fe2O3, SiO2 등의 산화물 나노입자를 코팅하는 많은 방법이 제안되어 있다[J. Phys. D: Appl. Phys., 29, p3173 (1996), Nano Lett., 3 (5), p681 (2003), J. of Colloid and Interface Sci., 286, p274 (2005), Chem. Commun., p758 (2005), Chem. Mater., 17(7), p1613 (2005)]In order to overcome the drawbacks of the vapor phase coating method, many methods for coating metals such as Au, Pd, and Pt and oxide nanoparticles such as SnO 2 , Fe 2 O 3 , and SiO 2 have been proposed by wet coating methods. J. Phys. D: Appl. Phys., 29, p3173 (1996), Nano Lett., 3 (5), p681 (2003), J. of Colloid and Interface Sci., 286, p274 (2005), Chem. Commun., P 758 (2005), Chem. Mater., 17 (7), p1613 (2005)]
한편, 전계방출소재는 전기전도도, 내화성 및 내구성 등의 물성이 요구되는 바, 탄소나노튜브에 다양한 금속을 코팅하여 적용하는 연구가 실시되고 있다.On the other hand, the field emission material is required for the physical properties such as electrical conductivity, fire resistance and durability, research is applied to the coating of various metals on carbon nanotubes.
그 중 티타늄 나노입자를 합성하고, 이를 탄소나노튜브 표면에 코팅하여 탄소나노튜브의 결함부위를 검지하는 연구도 소개되고 있다[J. Phys. Chem. B., 107, p2453 (2003)].Among them, a research on synthesizing titanium nanoparticles and coating them on the surface of carbon nanotubes to detect defects of carbon nanotubes has been introduced [J. Phys. Chem. B., 107, p 2453 (2003).
한편, 저차산화티타늄(TinO2n-1) 중의 일부는 전기적으로 전도성을 나타내기 때문에 저차산화티타늄 나노입자를 탄소나노튜브 표면에 코팅하면 전기적 특성 및 전계 방출 특성이 향상될 것으로 예측하고 본 발명을 고안하게 되었다. 저차산화티타늄 나노입자를 코팅하여 전계방출소자용으로 적용한 연구는 아직 없다. 그러나 일반적인 합성법으로는 TiO2 의 절연체의 형태로 합성되기 때문에, 일반적인 합성법으로 코팅을 실시할 경우 TiO2 나노입자가 코팅되고, TiO2 나노입자는 전기적으로 절연체이기 때문에 전계방출소자와 같이 전기적 특성이 중요시되는 용도에서는 성능향상을 기대할 수 없다. On the other hand, since some of the lower titanium oxide (Ti n O 2n-1 ) is electrically conductive, it is expected that the coating of the lower titanium oxide nanoparticles on the surface of the carbon nanotubes will improve the electrical properties and the field emission characteristics Was devised. There have been no studies on applying low-titanium oxide nanoparticles for field emission devices. However, since the general synthetic methods as will be synthesized in the form of an insulator of the TiO 2, when to carry out the coating in the general synthetic methods and coating the TiO 2 nanoparticles, TiO 2 because the nanoparticles are electrically insulation electric properties, such as field emission devices are In applications where it is important, performance improvement cannot be expected.
이에 본 발명자들은 저차산화티타늄 나노입자가 표면에 균일하게 코팅된 새로운 개념의 탄소나노튜브를 효과적으로 제조하고자 연구 노력하였다. 그 결과, 습식환원법을 이용하여 용액내에서 적절한 환원제를 첨가하는 조건하에서 수행하면, 탄소나노튜브 표면에서 저차산화티타늄 나노입자의 핵 생성과 동시에 성장이 가능하다는 것을 알게되어 본 발명을 완성하게 되었다.Therefore, the present inventors have tried to effectively prepare a new concept of carbon nanotubes in which low titanium oxide nanoparticles are uniformly coated on the surface. As a result, the present invention was completed by the wet reduction method under the condition of adding an appropriate reducing agent in the solution, and it was possible to simultaneously grow and nucleate low-titanium oxide nanoparticles on the surface of carbon nanotubes.
따라서, 본 발명은 저차산화티타늄 나노입자가 균일하게 코팅된 탄소나노튜브를 제조하는 방법을 제공하는 데 그 목적이 있다.Accordingly, an object of the present invention is to provide a method for producing carbon nanotubes uniformly coated with low titanium oxide nanoparticles.
본 발명은 5 ∼ 20 중량% 농도의 티타늄염 수용액에, 상기 티타늄에 대하여 탄소나노튜브를 0.1 ∼ 15 몰비로 분산시키고,The present invention is dispersed in a titanium salt aqueous solution of 5 to 20% by weight in concentration of 0.1 to 15 molar ratio of carbon nanotubes relative to the titanium,
상기 탄소나노튜브가 분산된 티타늄염 수용액에, 하이드라진 또는 이의 수화물의 환원제를 상기 티타늄에 대하여 10 ∼ 50 몰비로 적하하여 To a titanium salt aqueous solution in which the carbon nanotubes are dispersed, a reducing agent of hydrazine or a hydrate thereof is added dropwise to the titanium at 10 to 50 molar ratio.
저차산화티타늄 나노입자의 형성과 동시에 탄소나노튜브 표면에 코팅하는 방법에 그 특징이 있다.It is characterized by the method of coating the surface of carbon nanotubes with the formation of low-order titanium oxide nanoparticles.
이하, 본 발명을 상세히 설명하면 다음과 같다.Hereinafter, the present invention will be described in detail.
본 발명은 습식환원법을 이용하여 티타늄을 저차산화티타늄으로 환원시켜 입자의 핵생성과 동시에 탄소나노튜브 표면에 상기 저차산화티타늄 나노입자를 균일하게 코팅시키는 방법에 관한 것이다. The present invention relates to a method of uniformly coating the low-titanium oxide nanoparticles on the surface of carbon nanotubes at the same time as nucleation of particles by reducing titanium to low-titanium oxide using a wet reduction method.
저차산화티타늄은 특정 조성 영역(TinO2n-1, n=4, 5)에서 전기전도도가 103 S/cm이상으로 높고 내화성이 우수하여 전계방출소자로 사용되는 탄소나노튜브의 표면에 코팅할 경우 구동전압(turn-on voltage)이 낮아져서 수명을 향상시킬 수 있을 것으로 기대되는 물질로 이를 선택 사용한 것이다. Low Titanium Oxide is coated on the surface of carbon nanotubes used as field emission devices due to its high electrical conductivity of 10 3 S / cm or more and high fire resistance in specific composition areas (Ti n O 2n-1 , n = 4, 5). In this case, the turn-on voltage is lowered and the life expectancy can be improved.
또한 본 발명은 상온에서 저차산화티타늄을 생성함과 동시에 성장시켜 탄소나노튜브 표면에 균일하게 코팅하는 데 기술구성상의 특징이 있는 것이다.In addition, the present invention is characterized by the technical configuration in uniform coating on the surface of carbon nanotubes by growing at the same time to produce a low titanium oxide at room temperature.
종래에 저차산화티타늄 입자는 1300 ℃ 이상의 고온에서 수소분위하에서 열처리하여 제조되었기 때문에 입자크기가 수 ㎛ 수준이고, 직경이 나노미터인 탄소나노튜브의 표면에 균일하게 코팅하는 것이 사실상 불가능하다. 즉, 탄소나노튜브에 저차산화티타늄 나노입자를 균일하게 코팅하기 위해서는 종래의 수소환원법으로 불가능하기 때문에 습식환원법으로 적절한 환원제를 사용한 특정의 조건하에서 저차산화티타늄 나노입자를 합성하되 탄소나노튜브 표면에서의 불균일 (heterogeneous) 핵생성(nucleation)과 입자성장(growing)을 동시에 수행함으로써, 나노크기, 구체적으로 2 ∼ 20 ㎚ 범위의 저차산화티타늄 입자의 합성과 동시에 이를 탄소나노튜브의 표면에 균일하게 코팅하는 방법으로 당 업자에 의해 결코 용이하게 발명할 수 없는 것이다.
본원발명의 저차산화티타늄 입자의 생성은 상온에서 티타늄염(삼염화티타늄)과 환원제(하이드라진)를 이용한 환원반응을 수행한 결과로 얻어지는 것이다.
통상적으로 티타늄 염의 상온 수화반응을 통해서는 비정질 수산화티타늄 Ti(OH)x의 생성이 일반적이며, 이를 300 ℃ 정도의 고온으로 열처리해야만 TiO2로 전환시킬 수 있다. 본원발명에서는 티타늄 염의 상온 수화(습식)반응에, 환원제(하이드라진)을 도입함으로써 TiO2나 Ti(OH)x가 아닌 저차산화 티타늄을 얻게 된다는 것에 기술구성상의 특징이 있다. 이때, 환원제의 사용량이 본원발명에서 제시한 범위를 벗어나는 경우에는 본원발명과 같은 Ti4O7을 티타늄염을 사용하여 상온에서 수행되는 환원반응으로는 목적으로 하는 효과 달성이 불가능하다.
즉, 본원발명은 상온에서의 습식환원법을 수행하여 환원차수를 제어함으로써 저차산화티타늄 입자를 생성한다.
또한, 불균일 핵생성은 결정핵이 결정화하기 전에 이미 존재하거나 결정핵이 될 수 있는 이종물질(異種物質)이 존재하는 경우의 핵생성을 의미하는 것이고, 균일 핵생성은 초기에 미결정인 결정핵이 없어 모든 곳에서 결정이 생길 확률이 같으며 액체상의 온도요동에 의한 밀도 요동으로 결정핵이 생성되는 것을 의미하는 것으로 이는 당 분야에서 일반적으로 알려져 있다.
일반적으로 균일 핵생성이 일어나기 위한 에너지 장벽에 비하여 불균일 핵생성이 일어나기 위한 에너지 장벽이 낮기 때문에, 반응계에서 불균일 핵생성이 일어날 수 있는 이종물질(예, 씨앗입자, CNT와 같은 1차원 나노구조체, 반응기의 벽면 등)이 있으며 균일 핵생성 보다는 불균일 핵생성이 에너지적으로 더 우선해서 일어난다. 이에 본원발명은 CNT를 불균일 핵생성의 이종물질로 작용하도록 반응계에 미리 분산시켜 나노입자의 불균일 핵생성을 유도하여 상기와 같은 불균일 핵생성을 유도한다. Since the low titanium oxide particles are conventionally prepared by heat treatment under a hydrogen atmosphere at a high temperature of 1300 ° C. or higher, it is virtually impossible to uniformly coat the surface of carbon nanotubes having a particle size of several μm and a diameter of nanometers. In other words, in order to uniformly coat the low-titanium oxide nanoparticles on the carbon nanotubes, it is impossible to perform the conventional hydrogen reduction method. Thus, the low-titanium oxide nanoparticles should be synthesized under the specific conditions using a suitable reducing agent by the wet reduction method. By simultaneously performing heterogeneous nucleation and particle growth, the synthesis of nano-sized, particularly low-order titanium oxide particles in the range of 2 to 20 nm and uniform coating on the surface of the carbon nanotubes It can never be easily invented by those skilled in the art.
The production of the lower titanium oxide particles of the present invention is obtained by performing a reduction reaction using titanium salt (titanium trichloride) and a reducing agent (hydrazine) at room temperature.
Typically, the production of amorphous titanium hydroxide Ti (OH) x is common through the room temperature hydration reaction of titanium salt, which can be converted to TiO 2 only by heat treatment at a high temperature of about 300 ° C. In the present invention, there is a characteristic feature of the technical structure that a low-order titanium oxide, not TiO 2 or Ti (OH) x, is obtained by introducing a reducing agent (hydrazine) in the room temperature hydration (wet) reaction of the titanium salt. At this time, when the amount of the reducing agent is out of the range set forth in the present invention, it is impossible to achieve the desired effect by the reduction reaction performed at room temperature using a titanium salt of Ti 4 O 7 as the present invention.
That is, the present invention produces low titanium oxide particles by performing a wet reduction method at room temperature to control the reduction order.
In addition, heterogeneous nucleation refers to nucleation when heterogeneous substances that exist or may be present before crystallization crystallizes, and homogeneous nucleation refers to nuclei that are initially undetermined. It is generally known in the art that crystal nuclei are formed by density fluctuations caused by temperature fluctuations in liquid phase.
In general, because the energy barrier for heterogeneous nucleation is lower than the energy barrier for homogeneous nucleation, heterogeneous materials (e.g., seed particles, one-dimensional nanostructures such as CNTs, reactors, etc.) may cause heterogeneous nucleation in the reaction system. Walls, etc.), and heterogeneous nucleation takes place more energically than uniform nucleation. Therefore, the present invention induces heterogeneous nucleation as described above by dispersing CNTs in advance in the reaction system to act as heterogeneous material of heterogeneous nucleation.
본 발명에 따른 탄소나노튜브 표면에 저차산화티타늄 나노입자를 코팅하는 방법을 보다 구체적으로 살펴보면 다음과 같다.Looking at the method of coating the low-titanium oxide nanoparticles on the surface of the carbon nanotubes according to the present invention in more detail.
먼저, 티타늄염 수용액에 탄소나노튜브를 분산시킨다.First, carbon nanotubes are dispersed in an aqueous titanium salt solution.
상기 티타늄염은 당 분야에서 일반적으로 사용되는 것으로 특별히 한정하지는 않으나, 구체적으로 삼염화티타늄(TiCl3), 티타늄 알콕사이드(Titanium alkoxide), 질산티타늄(TiNO3)4 및 황산티타늄(Ti2(SO4)3)등을 사용할 수 있다. 바람직하기로는 가격, 분산매에 대한 용해도 등을 고려하여 삼염화티타늄(TiCl3)을 사용하는 것이 좋다.The titanium salt is generally used in the art, but is not particularly limited, and specifically, titanium trichloride (TiCl 3 ), titanium alkoxide, titanium nitrate (TiNO 3 ) 4 and titanium sulfate (Ti 2 (SO 4 )). 3 ) can be used. Preferably, titanium trichloride (TiCl 3 ) is used in consideration of price, solubility in a dispersion medium, and the like.
이러한 티타늄 염은 5 ∼ 20 중량% 농도의 수용액을 유지하는 바, 상기 농도가 5 중량% 미만이면 임계 핵생성 농도보다 낮아서 핵의 밀도가 낮고, 20 중량%를 초과하는 경우에는 과포화에 의한 미용해 원료에 의한 조성 불균일 및 넓은 입도분포 등의 문제가 발생하므로 상기 범위를 유지하는 것이 바람직하다. Such a titanium salt maintains an aqueous solution of 5 to 20% by weight. If the concentration is less than 5% by weight, the concentration of the titanium salt is lower than the critical nucleation concentration, and the density of the nucleus is low. It is preferable to maintain the above range because problems such as composition unevenness and wide particle size distribution due to raw materials occur.
상기 분산은 물을 용매로 수행되는 바, 보다 효과적인 분산을 위하여 초음파를 이용하여 10 ∼ 30분간 수행하는 것이 좋다.The dispersion is performed with water as a solvent, it is preferable to perform for 10 to 30 minutes using ultrasonic waves for more effective dispersion.
상기 탄소나노튜브상기는 티타늄에 대하여 0.1 ∼ 15 몰비 범위로 사용하는 바, 상기 사용량이 0.1 몰비 미만이면 탄소나노튜브 표면에 코팅되는 나노입자가 부족하고 15 몰비를 초과하는 경우에는 코팅되고 남는 나노입자가 독립적으로 응집되어 따로 존재하는 문제가 발생하므로 상기 범위를 유지하는 것이 바람직하다.The carbon nanotubes are used in the range of 0.1 to 15 molar ratios with respect to titanium. If the amount is less than 0.1 molar ratio, the nanoparticles coated on the surface of the carbon nanotubes are insufficient, and when the molar ratio exceeds 15 molar ratios, the remaining nanoparticles are coated. It is preferable to maintain the above range because the problem of agglomerated independently occurs.
다음으로, 상기 탄소나노튜브가 분산된 티타늄염 수용액에, 하이드라진 (N2H4)또는 이의 수화물 (N2H4·xH2O)의 환원제를 적하한다. 상기 환원제는 통상적으로 열의 발생이 많으므로 서서히 적하하는 것이 바람직하다. Next, a reducing agent of hydrazine (N 2 H 4 ) or a hydrate thereof (N 2 H 4 · xH 2 O) is added dropwise to the aqueous titanium salt solution in which the carbon nanotubes are dispersed. Since the said reducing agent usually generate | occur | produces heat normally, it is preferable to add gradually.
또한 적하는 상온에서 비이커에 액적으로 떨어뜨리는 조건에서 수행되는 바, 균일한 환원반응을 유도하기 위하여 교반을 수행하는 것이 바람직하다.In addition, the dropping is carried out under the conditions of dropping the droplets in the beaker at room temperature, it is preferable to perform the stirring to induce a uniform reduction reaction.
상기 환원제는 티타늄에 대하여 10 ∼ 50 몰비, 바람직하기로는 20 ∼ 30 몰비 범위로 사용하는 바, 상기 사용량이 10 몰비 미만이면 환원되지 못하는 삼염화 티타늄이 잔류하고 50 몰비를 초과하는 경우에는 환원에 사용되지 못한 환원제의 잔류와 과도한 부산물이 발생되는 문제가 일어나므로 상기 범위를 유지하는 것이 바람직하다.The reducing agent is used in a range of 10 to 50 molar ratios, preferably 20 to 30 molar ratios with respect to titanium. If the amount is less than 10 molar ratios, titanium trichloride, which cannot be reduced, remains and is not used for reduction. It is desirable to maintain this range because of the problem of poor residuals and excessive by-products.
상기 과정으로 탄소나노튜브 표면에서 저차산화티타늄 입자가 핵 생성과 동시에 성장하여 균일하게 코팅된다.In the above process, low titanium dioxide particles are grown on the surface of the carbon nanotubes at the same time as nucleation and are uniformly coated.
상기에서 제조된 코팅된 탄소나노튜브는 여과 및 증류수를 이용한 세척과정 으로 정제된 저차산화티타늄이 코팅된 탄소나노튜브를 얻는다.The coated carbon nanotubes prepared above are obtained with purified titanium dioxide coated carbon nanotubes by filtration and washing with distilled water.
이와 같은 본 발명을 실시예에 의거하여 보다 구체적으로 설명하겠는바, 본 발명이 다음 실시예에 의하여 한정되는 것은 아니다.The present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.
실시예 1Example 1
10 중량%의 삼염화티타늄(TiCl3) 수용액 5 cc에 0.0182 g의 탄소나노튜브를 넣고 10분간 초음파 처리하여 분산시켰다. 상기 균일 분산된 출발원료에 6 g의 하이드라진 수화물을 서서히 적하시키면서 티타늄의 환원을 유도하였다. 이때, 티타늄과 하이드라진의 몰비가 1:30으로 유지하며, 균일한 환원반응을 유지하기 위하여 용액을 교반시켰다. To 5 cc of 10 wt% titanium trichloride (TiCl 3 ) aqueous solution, 0.0182 g of carbon nanotubes were added and sonicated for 10 minutes. 6 g of hydrazine hydrate was slowly added dropwise to the uniformly dispersed starting material to induce reduction of titanium. At this time, the molar ratio of titanium and hydrazine is maintained at 1:30, and the solution was stirred to maintain a uniform reduction reaction.
상기 반응이 완료되면 급냉하여 10분간 초음파 처리를 수행하였다. 이후에 코팅된 탄소나노튜브의 회수를 위하여 기공크기가 0.2 ㎛인 여과지를 이용하여 여과하고 과량의 증류수를 이용하여 2회 이상의 세척과정을 수행하였다.When the reaction was completed, it was quenched and sonicated for 10 minutes. Thereafter, in order to recover the coated carbon nanotubes, the filter was filtered using a filter paper having a pore size of 0.2 μm, and two or more washing processes were performed using excess distilled water.
도 1은 상기에서 제조된 저차산화티타늄 나노입자가 코팅된 탄소나노튜브의 투과전자현미경(TEM) 사진이고, 도 2는 투과전자현미경 사진으로부터 측정된 평균 입자크기 및 표준편차를 나타낸 것으로, 크기가 2 ∼ 3 nm인 저차산화티타늄 나노입자가 균일하게 코팅되어 있음을 확인하였다. 1 is a transmission electron microscope (TEM) picture of the carbon nanotubes coated with the low-titanium oxide nanoparticles prepared above, and FIG. 2 shows the average particle size and the standard deviation measured from the transmission electron microscope picture. It was confirmed that low titanium oxide nanoparticles having a thickness of 2 to 3 nm were uniformly coated.
도 3은 탄소나노튜브 표면에 코팅된 나노입자의 X-선 회절분석 결과를 나타 낸 것으로 X-선 회절분석 결과로부터 생성된 나노입자는 주요상은 비정질 Ti4O7 상이며, Ti5O9상이 미량 함유되어 있음을 확인하였다.FIG. 3 shows the results of X-ray diffraction analysis of nanoparticles coated on the surface of carbon nanotubes. The nanoparticles produced from the results of X-ray diffraction analysis have an amorphous Ti 4 O 7 phase and a Ti 5 O 9 phase. It was confirmed that it contained a trace amount.
이상에서 설명한 바와 같이, 본 발명은 습식환원법으로 저차산화티타늄 나노입자의 핵 생성과 동시에 입자성장시켜 탄소나노튜브 표면에 균일하게 코팅하는 방법으로, 상기 방법으로 저차산화티타늄 나노입자가 균일하게 코팅된 탄소나노튜브는 전기전도도, 전계 방출 성능 등의 향상이 기대되므로 전계 방출 디스플레이의 전계방출 팁으로의 응용이 기대된다.As described above, the present invention is a method of uniformly coating the surface of the carbon nanotubes by simultaneously growing the nucleation of the low-titanium oxide nanoparticles by the wet reduction method, the low-titanium oxide nanoparticles are uniformly coated by the above method Carbon nanotubes are expected to have improved electrical conductivity, field emission performance, and so on, and are expected to be applied as field emission tips in field emission displays.
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