• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.4
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• pp.337-341
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• 2005

The degradation of IPA according to coating conditions was examined by $TiO_2/P-25-coated$ POF. In the photoactivity of $TiO_2-coated$ POF, ethanol solvent was higher activity than other solvents. Inorganic(KR-400), organic(A-9540) and inorganic$\cdot$organic hybrid(GPTMS, TMOS) resins were used as binder. Organic binder(A-9540) showed the highest activity for degradation of IPA, but organic binder was decomposed by $TiO_2$. Inorganic binder had lower binder ability than others, and lower adhesive than organic binders. In TMOS as inorganic · organic hybrid binder, activity of IPA degradation was decreased by addition of TMOS when the ratio of TMOS and P-25 was changed from 0.05 to 1.

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1753-1758
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• 2012

A novel, efficient and controlled protocol for the synthesis and enhanced photocatalytic activity of $Au@TiO_2$ nanocomposite is developed. $TiO_2$ (P25) was pretreated by employing UV light (${\lambda}$ = 254 nm) and the pretreated $TiO_2$ was uniformly decorated by gold nanoparticles (AuNPs) in presence of sodium citrate and UV light. UV pretreatment makes the $TiO_2$ activated, as electrons were accumulated within the $TiO_2$ in the conduction band. These accumulated electrons facilitate the formation of AuNPs which were of very small size (2-5 nm), similar morphology and uniformly deposited at $TiO_2$ surface. It leads to formation of stable and crystalline $Au@TiO_2$ nanocomposites. The rapidity (13 hours), monodispersity, smaller nanocomposites and easy separation make this protocol highly significant in the area of nanocomposites syntheses. As-synthesized nanocomposites were characterized by TEM, HRTEM, TEM-EDX, SAED, XRD, UV-visible spectrophotometer and zeta potential. Dye degradation experiments of methyl orange show that type I ($Au@TiO_2$ nanocomposites in which $TiO_2$ was pretreated with UV light) has enhanced photocatalytic activity in comparison to type II ($Au@TiO_2$ nanocomposites in which $TiO_2$ was not pretreated with UV light) and $TiO_2$ (P25). This shows that pretreatment of $TiO_2$ provides type I a better catalytic activity.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.635-635
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• 2013

We report three-dimensional polycrystalline anatase TiO2 structures (3D a-TiO2) for environmental and bio-medical applications. The 3D a-TiO2 was synthesized without thermal treatment by the growth of rod-like polycrystals on Degussa P25 (P25) via low temperature (< $85^{\circ}C$) modified alkali hydrothermal processing. X-ray diffraction and high-resolution transmission electron microscopic results showed that the rod-like polycrystals of 3D a-TiO2 possessed the highly anatase nanostructures. The photocatalytic activity of 3D a-TiO2 was found to be 2.2 times higher than that of P25. The recyclability of the 3D a-TiO2 was found to be high: the decolorization rate was 94.8% of the initial value after fifteen cycles. In addition, 3D a-TiO2 exhibited excellent antibacterial activities for the sterilization of gram-negative Escherichia coli (E. coli) and gram-positive Staphylococcus aureus (S. aureus). Even at the 10th recycled use, more than 98.4% of E. coli and S. aureus can be killed. These results indicated that 3D a-TiO2 might have utility in several promising applications such as photocatalytic water/air purification and bactericidal agents.

• Applied Chemistry for Engineering
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• v.21 no.4
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• pp.405-410
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• 2010

The photovoltaic performance of DSSCs fabricated with different electrode thickness and different annealing temperature with the P25 $TiO_2$ and the Dyesol $TiO_2$ was measured. Thickness change of $TiO_2$ electrodes was measured using cross-sectional FE-SEM before and after annealing. Photovoltaic efficiencies of DSSCs were also measured by changing annealing temperature of platinum (Pt) paste on the counter electrode. Photovoltaic performances of DSSCs made with one layer of P25 (${\sim}20.4\;{\mu}m$) and one layer of Dyesol $TiO_2$ (${\sim}9.1\;{\mu}m$) annealed at $500^{\circ}C$ for 30 min. showed highest efficiencies of 3.8% and 5.8%, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1073-1081
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• 2000

The photo-oxidation of an aqueous humic acid solution using $TiO_2$ sols. which is transparent in visible range, was studied. The $TiO_2$ sols were prepared by a process wherein hydrogen peroxide was added to a gel of $TiO(OH)_2$ originated from hydrolysis of $TiCl_4$, and the resulting titanium peroxo solution(TPS) was heated. The concentration of $TiO_2$ used for photo-oxidation was about 100ppm, determined by comparing the photoluminescence(PL) intensity measured as a function of $TiO_2$ concentration. $TiO_2$ sols aged at $100^{\circ}C$ for more than 12h were found to exhibit a maximum rate in photocatalytic decomposition of humic acid. and the efficiency was better than that of Degussa P25. In addition, the resulting aqueous humic acid after photocatalytic decomposition with sols had an excellent transmittance of visible light, while that treated with Degussa P25 was still turbid. caused by $TiO_2$ particles.

• Journal of Technologic Dentistry
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• v.21 no.1
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• pp.5-14
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• 1999

Glass ceramics for dental crown prosthesis were prepared by crystallization of CaO-MgO-SiO2-$P_2O_5-TiO_2$ glasses. Their crystallization behaviors have been investigated as a function of heattreatment temperature, holding time and chemical composition in relation to mechinical properties. Crystallization peak temperatures were determined by differential thermal analysis(DTA). Crystalline phases and mircostructures of heat-treated sample were determined by the means of powder X-ray diffraction(XRD) and scanning electron microscopy(SEM). The final crystalline phase assemblages and the microstructures of the samples were found to be dependent on glass compositions, heattreatment temperature, and holding time. 1st crystallization peak temperature(TP), affected strongly by apatite, was found to be increased or decreased. From the experiment, the following results were obtained : 1. The crystallization peak temperature($T_P$) formed by apatite increased until adding up to 9wt% $TiO_2$ to base glass composition, then decreased above that. 2. Apatite($Ca_{10}P_6O_{25}$), whitlockite(${\beta}-3CaO-P_2O_5$), $\beta$-wollastonite($CaSiO_3$), magnesium tianate($MaTiO_3$) and diopside(CaO-MgO-$2SiO_2$) crystal phase were precipitated in MgO-CaO-$SiO_2-TiO_2-P_2O_5$ glass system containing 9wt% and 11wt% of $TiO_2$ 3. Vickers hardness of samples increased with increasing heat-treatment temperature and Vickers hardness of S415T9 samples heat-treated at 1075 was approxi-mately 813Kg $mm^{-2}$ as maximum value. 4. Vickers hardness of samples increased due to precipitation of apatite, whitlockite, $\beta$-wollastonite, magnesium titanate, and diopside crystal phases within glass matrix.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2004.05a
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• pp.234-239
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• 2004

본 연구에서는 마이크로파용 유전재료로서 널리 사용되고 있는 BNT($BaO-Nd_{2}O_{3}-TiO_{2}$)계 세라믹스를 기본조성으로 하고, 저융점의 phoshpate계 유리 프릿의 첨가를 통해 LTCC(Low Temperature Cofired Ceramic)에 적용 가능한 유전율을 가진 조성을 개발 하고자, $70P_{2}O_{5}-5B_{2}O_{3}-(25-x)BaO-xNa_{2}O$ 유리를 제조 및 특성을 평가하였다. 또한, BNT계 세라믹스에 glass frit을 5 - 15 wt% 범위에서 첨가하고, $800 - 950^{\circ}C$의 온도범위에서 소결하여 제조된 유리-세라믹 복합체의 소결특성 및 유전특성을 조사하였다.

• Journal of the Korean Chemical Society
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• v.46 no.1
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• pp.64-68
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• 2002

Photocatalytic treatment of aqueous cyanide was studied using both commercial and home-made $TiO_2$'s as catalysts. Among the catalysts, $TiO_2$ made from $Ti(OC_3H_7)_4$ as a precursor showed the highest activity for the degradation of cyanide exceeding a commercial catalyst of Degussa P25. The difference in activities of the catalysts was mainly related to the surface properties of the catalysts such as the ratio of acidic to basic hydroxyl groups. For the catalyst which showed the highest activity, partially reduced $TiO_2$ showed better activity than calcined one.

• Journal of the Korean Ceramic Society
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• v.31 no.11
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• pp.1337-1345
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• 1994

Glasses in the system of 45CaO-25TiO2-30P2O5 containing 1 mole% of M2O(M=Li, Na, K) were melted and crystallized. And their crystal phases were Ca3(PO4)2, CaTi4(PO4)6, and TiO2. Porous glass-ceramics with skeleton of two crystal phase CaTi4(PO4)6 and TiO2 were prepared by selective leaching of Ca3(PO4)2 with 0.1 N-HCl. Glass transition temperature(Tg) and crystallization temperature(Tc) were decreased by addition of 1 mole% alkali metal oxide. Pore size of porous glass-ceramics was increased with increasing heat treatment temperature and its dependence on heat treatment temperature was decreased with addition of Na2O and K2O. It was found that porous glass-ceramics of parent glass and containing 1mole% M2O(M=Li, Na, K) composition had maximum specific surface area, porosity and maximum of crystallzed phase by heat treatment at 80$0^{\circ}C$, 76$0^{\circ}C$, 78$0^{\circ}C$, 80$0^{\circ}C$ respectively.

• Clean Technology
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• v.28 no.2
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• pp.147-154
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• 2022

Titanate nanotubes (TNTs) were synthesized via alkaline hydrothermal treatment using commercial TiO₂ nanoparticles (P25). The TNTs were prepared at various TiO₂/NaOH ratios, hydrothermal temperatures, and hydrothermal times. The synthesized catalysts were characterized by X-ray diffraction, field-emission scanning electron microscopy, N₂ adsorption-desorption isotherms, field-emission transmission electron microscopy, and ultraviolet-visible spectroscopy. TNTs were generated upon a decrease in the TiO₂/NaOH ratio due to the dissolution of TiO₂ in the alkaline solution and the generation of new Ti-O-Ti bonds to form titanate nanoplates and nanotubes. The hydrothermal treatment temperature and time were important factors for promoting the nucleation and growth of TNTs. The TNT catalyst with the largest surface area (389.32 m² g^-1) was obtained with a TiO₂/NaOH ratio of 0.25, a hydrothermal treatment temperature of 130 ℃, and a hydrothermal treatment time of 36 h. Additionally, we investigated the photocatalytic activity of methyl violet 2B (MV) over the TNT catalysts under UV irradiation and found that the degradation efficiencies of the TNTs were higher than that of P25. Among the TNT catalysts, the TNT catalyst that was hydrothermally synthesized for 36 h (TNT 36 h) exhibited a 96.9% degradation efficiency and a degradation rate constant that was 4.8 times higher than P25 due to its large surface area, which allowed for more contact between the MV molecules and TNT surfaces and facilitated rapid electron transfer. Finally, these results were correlated with the specific surface area.