• Applied Chemistry for Engineering
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• v.29 no.3
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• pp.298-302
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• 2018

Photocatalytic properties of nitrogen doped titanium dioxide were investigated. Photocatalytic degradation of methylene blue under UV and visible light was carried out to characterize N-doped $TiO_2$. The result of XPS indicated that nitrogen atoms substitute for oxygen sites within the crystal structure of $TiO_2$. In the UV-Vis DRS spectra, N-doped amorphous $TiO_2$ absorbed UV light with little absorption of visible light, while the absorption of visible light of amorphous/anatase $TiO_2$ remarkably increased. Methylene blue photocatalytic degradation appeared by the irradiation of UV or visible light onto the N-doped anatase phase of $TiO_2$. However, the degradation rate of visible light was lower than that of UV light. The photocatalytic degradation rate of the amorphous/anatase $TiO_2$ sample was higher than that of the anatase $TiO_2$. These results indicate that the high surface area of amorphous/anatase $TiO_2$ sample, which was about three times larger than those of the anatase $TiO_2$ sample, may be related to small particles of N-doped anatase $TiO_2$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.4
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• pp.166-173
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• 2021

The rutile phase of TiO₂ forms a stable phase at high temperatures compared to anatase phase, but the stable temperature range of anatase changes depending on the synthesis conditions. In this study, nano-sized TiO₂ was synthesized by the Sol-gel method using TiOSO₄ and a mixed solvent of ethanol and distilled water, and the phase change of anatase and rutile according to pH and heat treatment temperature was investigated. Changes in the ratio of anatase and rutile were observed by changing the pH (3, 5, 7, 9) and heat treatment temperature (500, 600, 700, 800, 900℃) conditions of the prepared TiO₂. As a result of observing these changes through XRD and FE-SEM analysis, anatase TiO₂ at 500℃ and rutile TiO₂ at 900℃ were observed. According to the pH, at these intermediate temperatures of 600, 700 and 800℃, the ratio of anatase and rutile changes. At 700℃, it was concluded that pH = 3~5 had a larger ratio of anatase TiO₂, and pH = 7~9 had a larger ratio of rutile TiO₂.

• Journal of Korean Society on Water Environment
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• v.35 no.6
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• pp.550-556
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• 2019

This study was carried out to improve the photocatalytic reaction of TiO₂ photocatalyst. During the photocatalytic reaction, OH radicals are generated and they have an excellent oxidation capability for wastewater treatment. To evaluate the OH radicals generated according to crystallographic structure of TiO₂ nanotubes photocatalyst, a probe compound, 4-Chlorobenzoic acid was monitored to evaluate OH radical. Ultraviolet light was applied for photocatalytic reaction of TiO₂. The 4-Chlorobenzoic acid solution was prepared at laboratory. TiO₂ nanotube was grown on titanium plate by using anodization method. The annealing temperature for TiO₂ nanotube was varied from 400 to 900 ℃ and the crystal forms of the TiO₂ nanotube was analyzed. Depending on annealing temperature, TiO₂ nanotubes have shown different crystal forms; 100% anatase (0 % rutile), 18.4 % rutile (81.6 % anatase), 36.6 % rutile (63.4 % anatase) and 98.6% rutile (1.4% anatase). As the annealing temperature increases, the rutile ratio increases. OH radical generation from 18.4 % rutile TiO₂ nanotube plate was about 3.8 times higher than before annealing and 1.4 times higher than only 100 % anatase-TiO₂ nanotube. The efficiency of the 18.4% rutile TiO₂ nanotube was the best in comparison to TiO₂ nanotube with 18.4 %, 36.6 % and 98.6 % rutile. As a result, photocatalytic ability of 18.4 % rutile-TiO₂ nanotube plate was higher than 100 % anatase-TiO₂ nanotube plate.

• Journal of Powder Materials
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• v.25 no.3
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• pp.257-262
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• 2018

The coupling of two semiconducting materials is an efficient method to improve photocatalytic activity via the suppression of recombination of electron-hole pairs. In particular, the coupling between two different phases of $TiO_2$, i.e., anatase and rutile, is particularly attractive for photocatalytic activity improvement of rutile $TiO_2$ because these coupled $TiO_2$ powders can retain the benefits of $TiO_2$, one of the best photocatalysts. In this study, anatase $TiO_2$ nanoparticles are synthesized and coupled on the surface of rutile $TiO_2$ powders using a microemulsion method and heat treatment. Triton X-100, as a surfactant, is used to suppress the aggregation of anatase $TiO_2$ nanoparticles and disperse anatase $TiO_2$ nanoparticles uniformly on the surface of rutile $TiO_2$ powders. Rutile $TiO_2$ powders coupled with anatase $TiO_2$ nanoparticles are successfully prepared. Additionally, we compare the photocatalytic activity of these rutile-anatase coupled $TiO_2$ powders under ultraviolet (UV) light and demonstrate that the reason for the improvement of photocatalytic activity is microstructural.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.1 no.2
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• pp.57-62
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• 2000

The photocatalytic degradation of trichloroethylene(TCE) in water on various types of$TiO_2$ was studied. Surface properties of $TiO_2$were characterized by XRD, SEM, and BET in our previous work(23) . $TiO_2$from Aldrich has 100$\%$pure anatase, TiO$_2$from KIER has 100$\%$ pure rutile structure, and P25-TiO$_2$from Degussa has mixed structure of anatase(75$\%$) and rutile(25$\%$) . Firstly, optimum conditions for TCE degradation were examined in this study. Results showed that optimum loading amount of catalyst was 0.1 wt% and recirculation flow rate of mixture(distilled water and TCE) was 200 cc/min. Secondly, the effect of $TiO_2$structure on TCE degradation was examined. Results revealed that anatase structure generally has better photocatalytic activity than rutile structure. Especially, mixed structure(Degussa P25-$TiO_2$) has the highest activity due to small particle size and large specific surface area.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.480-483
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• 2001

Epitaxial rutile-$TiO_2$ and anatase-$TiO_2$ films were grown at $800^{\circ}C$ on $Al_2O_3$ (1102) and $LaAlO_3$ (001), respectively, using pulsed laser deposition. The formation of different phases on different substrates could be qualitatively explained by the atomic arrangements at the interfaces. We also successfully deposited epitaxial rutile-$TiO_2$ and anatase-$TiO_2$ films on conductive $RuO_2$ and $La_{0.5}Sr_{0.5}CoO_{3}$ electrodes, respectively. Using a Kelvin probe, we measured the photovoltaic properties of these multilayer structures. A rutile-$TiO_2$ film grown on $RuO_2$ showed a very broad peak in the visible light region. An epitaxial anatase-$TiO_2$ film grown on $La_{0.5}Sr_{0.5}CoO_{3}$ showed a strong peak with a threshold energy of 3.05 eV.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.480-483
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• 2001

Epitaxial rutile-TiO$_2$ and anatase-TiO$_2$ films were grown at 80$0^{\circ}C$ on $Al_2$O$_3$ (1102) and LaAlO$_3$ (001), respectively, using pulsed laser deposition. The formation of different phases on different substrates could be qualitatively explained by the atomic arrangements at the interfaces. We also successfully deposited epitaxial rutile-TiO$_2$ and anatase-TiO$_2$ films on conductive RuO$_2$ and La$_{0.5}$Sr$_{0.5}$CoO$_3$ electrodes, respectively Using a Kelvin probe, we measured the photovoltaic properties of these multilayer structures. A rutile-TiO$_2$ film grown on RuO$_2$ showed a very broad peak in the visible light region. An epitaxial anatase-TiO$_2$ film grown on La$_{0.5}$Sr$_{0.5}$CoO$_3$ showed a strong peak with a threshold energy of 3.05 eV 3.05 eV

• Journal of Welding and Joining
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• v.21 no.4
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• pp.39-45
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• 2003

Nano-TiO$_2$ photocatalytic coatings were deposited on the stainless steel 304(50$\times$70$\times$3mm) by the APS(Atmospheric Plasma Spraying). Photocatlytic reaction was tested in MB(methylene blue) aqueous solution. For applying nano-TiO$_2$ powders by thermal spray, the starting nano-TiO$_2$ powder with 100% anatase crystalline was agglomerated by spray drying. Plasma second gas(H$_2$) flow rate and spraying distance were used as principal process parameters which are known to control heat enthalpy(heat input). The relationship between process parameters and the characteristics of microstructure such as the anatase phase fraction and grain size of the TiO$_2$ coatings were investigated. The photo-decomposition efficiency of TiO$_2$ coatings was evaluated by the kinetics of MB aqueous solution decomposition. It was found that the TiO$_2$ coating with a lower heat input condition had a higher anatase fraction, smaller anatase grain size and a better photo-decomposition efficiency.

• Rapid Communication in Photoscience
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• v.4 no.1
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• pp.9-11
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• 2015

The debromination of phenethyl bromide by the $B_{12}-TiO_2$ hybrid catalyst under UV light irradiation was investigated. The catalytic efficiency was dependent on the type of $TiO_2$. The anatase form of $TiO_2$ was superior to the rutile form of $TiO_2$. The selectivity of the product was also dependent on the crystal structure of $TiO_2$, and the rutile form of $TiO_2$ showed a high selectivity for the formation of the coupling product, 2,3-diphenylbutane, when compared to that of the anatase form of $TiO_2$.

• International Journal of Oral Biology
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• v.46 no.3
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• pp.105-110
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• 2021

The physicochemical properties of crystalline titanium dioxide nanoparticles (TiO₂ NPs) were investigated by comparing amorphous (amTiO₂), anatase (aTiO₂), metaphase of anatase-rutile (arTiO₂), and rutile (rTiO₂) NPs, which were prepared at various calcination temperatures (100℃, 400℃, 600℃, and 900℃). X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirmed that the phase-transformed TiO₂ had the characteristic features of crystallinity and average size. The surface chemical properties of the crystalline phases were different in the spectral analysis. As anatase transformed to the rutile phase, the band of the hydroxyl group at 3,600-3,100 cm^-1 decreased gradually, as assessed using Fourier transform infrared spectroscopy (FT-IR). For ultraviolet-visible (UV-Vis) spectra, the maximum absorbance of anatase TiO₂ NPs at 309 nm was blue-shifted to 290 nm at the rutile phase with reduced absorbance. Under the electric field of capillary electrophoresis (CE), TiO₂ NPs in anatase migrated and detected as a broaden peak, whereas the rutile NPs did not. In addition, anatase showed the highest photocatalytic activity in an UV-irradiated dye degradation assay in the following order: aTiO₂ > arTiO₂ > rTiO₂. Overall, the phases of TiO₂ NPs showed characteristic physicochemical properties regarding size, surface chemical properties, UV absorbance, CE migration, and photocatalytic activity.