• 상하수도학회지
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• 제13권3호
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• pp.101-106
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• 1999

This research aims to compare immobilized catalysts prepared by various methods and determine suitable $TiO_2$ catalyst for water purification. Sol-gel method by Anderson and powder coation method by Tanaka ate famous in the methods to immobilize catalyst. Therefore, the $TiO_2$ catalyst for this research was prepared by sol-gel method and powder coating method. Its structure was tested by X-ray diffractometer (XRD), Scanning electron microseope (SEM). Durability of a catalyst-support couple in an solution was investigated. too. Experimental results were summarized as following; i) Optimum ratio of Ti : $H_2O$ : $H^+$ to obtain stable sol was 1 : 10 : 0.1 and the XRD patterns of $TiO_2$ film immobilized by sol-gel method which were fired at $700^{\circ}C$ showed that the catalyst had an anatase structure. ii) The particle size of $TiO_2$ prepared by sol-gel method was less than $5{\mu}$, but it was observed that coated side was not unifiom. iii) Sol-gel method was very effective to obtain $TiO_2$ catalyst of thin film, but spreadability and durability of a catalyst-support couple in a solution were than $TiO_2$ film immobilized by powder coating method. iv) The particle size of $TiO_2$ immobilized by powder coating method was a little larger than it prepared by sol-gel method, but spreadability and uniformity of $TiO_2$ film and durability of a catalyst-support couple in a solution were better than it immobilized by sol-gel method.

• 한국세라믹학회지
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• 제41권6호
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• pp.471-475
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• 2004

졸겔 공정으로 안정한 TiO$_2$, SiO$_2$, PBA(Pseudo Boehemite Alumina) 졸을 제조하였다. 제조한 졸 용액은 비교적 균일한 10∼30nm의 입자크기를 나타내었다. TiO$_2$졸에 SiO$_2$졸의 첨가량이 증가함에 따라, anatase상에서 rutile 상으로 전이되는 상전이 온도를 $600^{\circ}C$ 이상으로 증가시켜 광분해 특성을 향상시켰다. 또한, TiO$_2$ 졸 용액에 SiO$_2$ 졸을 10∼30wt% 첨가하여 120$0^{\circ}C$ 이상의 고온 소성 후에도 anatase가 주된 상으로 소량의 rutile 상이 관찰되었다 또한 SiO$_2$20wt% 첨가 시, 최대의 광분해 특성을 나타내었다. 그러나, PBA 졸의 첨가는 첨가량에 관계없이 광분해 특성에 영향을 주지 않았다.

• 한국세라믹학회지
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• 제32권4호
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• pp.507-515
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• 1995

The monolithic dry gels of the Li2O-Al2O3-TiO2-SiO2 system were prepared by the sol-gel technique using metal alkoxides as starting materials to obtain monolithic glass-ceramics at low temperature without melting. Activation energy for the crystal growth of the gel with 6.05% TiO2, nucleating ageng, for the preparation of Li2O-Al2O3-TiO2-SiO2 system glass-ceramic was 101.14kcal/mol. As a result of the analysis of DTA & XRD, it was confirmed that the crytallization of Li2O-Al2O3-TiO2-SiO2 system glass-ceramic was the most efficient when 6.05% TiO2, nucleating agent, was added. $\beta$-eucryptite solid solution crystals and $\beta$-spodumene solid solution crystals were detected in the sample heat treated above 85$0^{\circ}C$. The sintered gel heat treated at 85$0^{\circ}C$ had the specific surface area of 185$m^2$/g, the pore volume of 0.19cc/g and the average pore radius of 20.8$\AA$. This shows that the sintered gel is also comparatively porous material. In temperature range of 25~85$0^{\circ}C$ thermal expansion coefficient of the specimen which was crystallized for 10hrs at 85$0^{\circ}C$ was 6.7$\times$10-7/$^{\circ}C$, which indicated that the crystallized specimen was turned out to be the glass-ceramic with low thermal expansion.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권7호
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• pp.349-353
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• 2006

[ $TiO_2-Nb_2O_5$ ] sol was prepared using sol-gel method. Crystalline properties of gel powder changed from rutile phase to anatase phase with increasing $Nb_2O_5$ additives at $800^{\circ}C$, while they retained rutile phase regardless of $Nb_2O_5$ additives at $900^{\circ}C,\;1,000^{\circ}C$. They retained amorphous phase from $50^{\circ}C\;to\;400^{\circ}C$, retained anatase phase from $500^{\circ}C\;to\;600^{\circ}C$ and had rutile phase over $700^{\circ}C$ at 1mole% $Nb_2O_5$ additive. After $TiO_2-Nb_2O_5$ sol retained low viscosity with normal chain structure for a long time, its viscosity increased fast with network structure. DTA properties of gel powder had endothermic reaction due to evaporation of propanol and water about $78^{\circ}C$, had exothermic reaction due to propanol combustion about $290^{\circ}C$ and had exothermic reaction due to changing of $TiO_2$ phase about $640^{\circ}C$.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 춘계학술발표강연 및 논문개요집
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• pp.207-207
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• 2003

최근 광촉매 재료로 각광받고 있는 TiO$_2$는 band gap 에너지가 3.0-3.2eV로 자외선 영역과 일부 가시광선 영역에서 활성을 갖는 것으로 알려져 있다. 따라서 용액 중에 결정화 및 안정화 되어있는 TiO$_2$의 band gap 에너지를 낮춘다면 가시광 영역의 광반응을 얻을 수 있다. 이에 본 연구는 G. Sato등이 제안한 방법으로 TiO$_2$ sol을 제조할 때 band gap 에너지를 낮추고자 천이 금속원소를 첨가하여 복합 및 담지된 TiO$_2$계 복합 sol을 합성하고자 하였다 출발원료는 TiC1$_4$를 가수분해하여 제조한 TiOCl$_2$에 천이금속원소인 V, Cr, Fe, Ni, Nb 등의 chloride 화합물을 첨가하여 중화 및 세척과정을 거친 후, 과산화수소수에 용해하여 전구체 용액인 titania peroxo용액을 제조하였다 제조된 전구체 용액은 온도와 시간을 변수로 각각 열처리하여 TiO$_2$계 복합 sol을 합성하였다. 제조된 시편은 X-선 회절 분석, 투과전자현미경, particle size analyzer, ζ-potential analyzer 및 UV-VIS Spectrometer 통을 이용하여 천이금속 첨가에 따른 TiO$_2$계 복합 sol의 형성과정과 특성변화를 관찰하였다.

• 한국환경과학회지
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• 제11권6호
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• pp.597-603
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• 2002

Photocatalytic degradation of phenol was carried out with UV-illuminated TiO$_2$-SiO$_2$ in aqueous suspension. TiO$_2$-SiO$_2$ catalysts were prepared by sol-gel method from the titanium isopropoxide and tetraethylorthosilicate at different Ti/Si ratio and some commercial TiO$_2$ catalysts were used as purchased. All catalysts were characterized by X-ray Diffraction(XRD) and BET surface area analyzer. The effect of reaction conditions, such as initial concentration of phenol, reaction temperature and catalyst weight on the photocatalytic activity was studied. In addition, TiO$_2$-SiO$_2$(49: 1) prepared by sol-gel method showed higher activity than commercial TiO$_2$catalysts on the photocatalytic degradation of phenol. The addition of SiO$_2$ into TiO$_2$hepled to increase the thermal stability of titania which suppressed the formation of anatase into rutile. The photocatalytic degradation of phenol showed pseudo-1st order reaction and the degradation rate increases with decreasing initial phenol concentration.

• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2365-2370
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• 2009

A working electrode in dye-sensitized solar cells was fabricated using $TiO_2$ colloidal sol prepared from titanium isopropoxide used as a starting material by applying the sol-gel method. The effect of aging times and temperatures on physical and chemical properties of $TiO_2$ sol particles was systematically investigated. Results showed that the crystallinity and average particle size of $TiO_2$ colloidal sol can be successfully controlled by the adjustment of aging time and temperature. The conversion efficiency of the repetitive dry coating films fabricated using the dried $TiO_2$ colloidal sol particles and hydroxypropyl cellulose binder (15%) was 10.31% with a high transparency.

• 전기학회논문지
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• 제56권7호
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• pp.1255-1260
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• 2007

[ $TiO_2-V_2O_5$ ] sol was prepared using sol-gel method. Sol changed to gel with hydrolysis and polymerization. DTA properties of gel powder had endothermic reaction due to evaporation of propanol about $80^{\circ}C$, had exothermic reaction due to combustion of propanol about $230^{\circ}C$ and had exothermic reaction due to combustion of alkyl group about $350^{\circ}C$. Crystalline properties of gel powder retained amorphous phase at $50^{\circ}C$, retained anatase phase from $400^{\circ}C\;to\;600^{\circ}C$ and had all rutile phase over $700^{\circ}C$ at 0.01mole $V_2O_5$ additive. The capacitance of thin films increased with increasing heat treatment temperature and thin films had best properties at $700^{\circ}C$. The capacitance of thin films increased a lot with decreasing measurement frequency.

• Bulletin of the Korean Chemical Society
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• 제23권5호
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• pp.745-748
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• 2002

A novel titania sol for the preparation of hydrophilic TiO2 films was synthesized from TiCl4. TiO2 films were prepared by spraying the sol on glass substrates and the hydrophilic properties of the films were invest igated with illumination of UV light. The contact angle of a water drop on the films decreased to less than 7˚, which indicates the excellent hydrophilicity of the TiO2 films.

• 분석과학
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• 제21권3호
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• pp.237-243
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• 2008

착체중합법과 sol-gel법을 이용하여 ZnO 나노입자 표면상에 $TiO_2$ 입자를 코팅한 나노 코아쉘 구조를 제조하였다. 착체중합법으로 제조된 ZnO 입자는 평균입도가 약 100 nm, sol-gel법으로 제조된 $TiO_2$ 입자는 10 nm 이하의 크기로 각각 구성되었다. $ZnO@TiO_2$ 나노 코아쉘 구조의 평균입도는 약 150 nm의 크기를 나타내었다. 착체중합법으로 제조된 구형의 ZnO 나노 입자는 콜로이드상의 $TiO_2$ 입자의 균일한 표면흡착으로 인해 착체중합법으로 제조된 ZnO 입자의 입자간 응집이 크게 제어되었다. ZnO와 $TiO_2$의 이종 입자간의 표면전하는 pH 7 근처의 중성 영역에서 iso-electric point (IEP)의 차이로 인하여 - 로 대전된 $TiO_2$와 + 로 대전된 ZnO 나노입자의 이종의 입자들이 쿨롱의 인력에 의해 서로간의 결합을 하게 되고, 결합을 이룬 $ZnO@TiO_2$ 나노 코아쉘 구조가 표면 전하가 zero가 되어 발생하게 된다.