• Rapid Communication in Photoscience
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• v.2 no.2
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• pp.64-66
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• 2013

Photoreduction of $CO_2$ into hydrocarbon fuels on the surface of photocatalyst is one of the breakthroughs in the field of photocatalysis. At present various approaches have been investigated with the aim of increasing the $CO_2$ conversion efficiency. The reactor for photoconversion of $CO_2$ plays a vital role in experimental setup. In this work an attempt was made to testify a newly designed the photoreactor for conversion of $CO_2$ into useful products. The photoreactor was specifically designed for simple operation bearing features of temperature and pressure control. The reactor has been tested successively with the standard titania, Degussa P25 yielding methane with moderate production rate of 30.8 $ppm{\cdot}g^{-1}{\cdot}h^{-1}$ under UV lamp with 365 nm wavelength. The methane yield obtained is comparable to the values reported in literature. Thus we anticipate that this experimental setup equipped with newly designed photoreactor can yield competitive amounts of fuels from $CO_2$ photoredcution via 365 nm UV light illumination on various photocatalysts.

• Journal of the Korean Ceramic Society
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• v.33 no.10
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• pp.1138-1146
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• 1996

Al2TiO5 powder was prepared by the sol-gel processing from th metal alkoxides ; aluminium sec-butoxide (Al(OC4H9)3 and tetraethyl orthotitanate (Ti(OC2H5)4) The particles of Al2TiO5 produced from alkoxides were measured to be below $1.5mutextrm{m}$ and mre than 90% weere below 1 ${\mu}{\textrm}{m}$ however those from commercial alumina and titania were over 0.5-7${\mu}{\textrm}{m}$ and only 60% were below 1${\mu}{\textrm}{m}$ and 90% were below 2.5${\mu}{\textrm}{m}$ Therefore Al2TiO5 powder produced from alkoxides had the narrower distributionin size than that produced from the commercial alumina and titania powders. The addition of mullite or Al2O3 powder to the prepared aluminum titanate inhibited the grain growth and this resulted in decreased and increase in density.

• Journal of the Korean Applied Science and Technology
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• v.28 no.3
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• pp.335-344
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• 2011

The pearlesent pigment has received attention in a diversity of fields like cosmetics, inks, paints and so on. Ferric Ferrocyanide, one of the nano sized pearlescent pigment, is a kind of surface modification pigment that covers a metal oxidized substance or a coloring agent with uniform thickness. Characteristics of pearlescent pigment are various interference color, intense gloss effect and a three-dimensional effect. We synthesised the pearlesent pigment that ferric ferrocyanide can be deposited on the titania/mica surface by hydrothermal synthesis method. The process parameters are concentration of precursor, controlling pH and reaction temperature. The optimun conditions is that amount of iron(III) chloride hexahydrate is 3.1 wt% and amount of potassim ferrocynide trihydrate is 3.6 wt% in the started pH 4.5 at $70^{\circ}C$. The coating rate and coating efficiency of ferric ferrocyanide was about 1.47 % and 96.7 %, respectively. The synthesised pearlesent pigment was characterized by SEM, XRD, FT-IR and EDS.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.211-211
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• 2011

Nanostructures, with a diversity of shapes, built on substrates have been developed within many research areas. Lithography is one powerful, but complex, technique to make structures at the nanometer scale, such as platinum nanowires for studying CO catalytic reactions [1], or aluminum nanodisks for studying the plasmon effect [2]. In this work, we approach a facile method to construct nanostructures using noble metals on a titania thin film by using self-assembled structures as a pattern. Here, a large-scale silica monolayer is transferred to the titania thin film substrates using a Langmuir-Blodgett trough, followed by the deposition of a thin transition metal layer. Owing to the hexagonal close-packed structure of the silica monolayer, we would obtain a metal nanostructure that includes separated metallic triangles (islands) after removing the patterning silica beads. This nanostructure can be employed to investigate the role of metal-oxide interfaces in CO catalytic reactions by changing the patterning silica particles with different sizes or by replacing the oxide support. The morphology and chemical composition of the structure can be characterized by scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. In addition, we modify these islands to a connected island structure by reducing the silica size of the patterning monolayer, which is utilized to generating hot electron flow based on the localized surface plasmon resonance effect of the metal nanostructures.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.32 no.3
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• pp.294-301
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• 1996

To improve the corrosion resistance of stainless steel and Fe, the adherence between fIlm and substarte and the corrosion resistance to ceramic fIlm ($TiO_2$ and $ZrO_2$), coated by RF magnetron sputtering, were studied. The adherence index (X) was determined by the measure of micro - hardness test. Also, the corrosion resistance on oxide coatings was studied using electrochemical measurement. The main results obtained are as the following: 1) In the micro - hardness test, with 1J.UI1 thickness fIlm, it has only one the value of X. Above 2J.UI1 thickness fIlm, however, get another value ofX as the cracks in fIlm. 2) The adhensivity of titania ($TiO_2$) coated fIlm is superior to that of zirconia ($ZrO_2$) coated fIlm. 3) All oxide fIlm used adhere well on the mild materials such as pure steel than high intensity materials like stainless steel. 4) The corrosion resistance of zirconia coated materials was improved compared to titania coated materials.

• Journal of Industrial Technology
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• v.32 no.A
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• pp.95-102
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• 2012

To advance luminance efficiency of Titania at visible range, N-doped $TiO_2$ was prepared by using ammonium hydroxide as a source of nitrogen. The photoactivities of the synthesized $TiO_2$ were evaluated on the basis of degradation of humic acid in aqueous solutions with different light sources, UV-C, UV-A and fluorescent lamp. As a result, at UV-C is high efficiency $UV_{254}$ decrease and TOC removal. In this study, the best synthetic conditions of N-doped $TiO_2$ were 5.0 M of ammonium hydroxide concentration and calcination temperature of $550^{\circ}C$. The degradation rate of humic acid as an evaluation of photoactivities of the catalysts were conducted with pH variation, decrease rate of molecular absorption, removal rate of total organic carbon and fluorescece evolution for humic acid solution. XRD and SEM were applied for analysis of surface analysis of the catalysts.

• The Korean Journal of Ceramics
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• v.3 no.1
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• pp.52-56
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• 1997

The Pt doped $TiO_2$ composite membranes were prepared by the sol-gel process. The Pt doped titania sol was peptized with hydrochloric acid in the pH range of 1.23 to 1.32 at 5$0^{\circ}C$. The average particle size of the Pt doped titania sol was shown to be below 15nm and well dispersed in the solution. XPS show the Pt elements continuous and homogeneous dispersed in the $TiO_2$ membrane. The mean particle size of the Pt doped $TiO_2$ composite membrane has smaller than that of the undoped $TiO_2$ composite membrane. The average pore size of the Pt doped $TiO_2$ composite membrane was increased from 58 to 193 $\AA$ with firing temperature changed from 550 to 85$0^{\circ}C$. It was observed that the Pt doped $TiO_2$ composite membranes showed crack-free and homogeneous microstructue as well as narrow particle size distribution up to above 75$0^{\circ}C$.

• Membrane and Water Treatment
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• v.6 no.3
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• pp.251-262
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• 2015

In this work the preparation and characterization of a membrane containing a uniform mesoporous Titanium oxide top layer on a porous stainless steel substrate has been studied. The 316 L stainless steel substrate was prepared by powder metallurgy technique and modified by soaking-rolling and fast drying method. The mesoporous titania membrane was fabricated via the sol-gel method. Morphological studies were performed on both supported and unsupported membranes using scanning electron microscope (SEM) and field emission scanning microscope (FESEM). The membranes were also characterized using X-ray diffraction (XRD) and $N_2$-adsorption / desorption measurement (BET analyses). It was revealed that a defect-free anatase membrane with a thickness of $1.6{\mu}m$ and 4.3 nm average pore size can be produced. In order to evaluate the performance of the supported membrane, single-gas permeation experiments were carried out at room temperature with nitrogen gas. The permeability coefficient of the fabricated membrane was $4{\times}10^{-8}\;lit\;s^{-1}\;Pa^{-1}\;cm^{-1}$.

• Korean Journal of Metals and Materials
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• v.50 no.7
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• pp.523-530
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• 2012

We investigated the experimental method that uses the homogeneous precipitation method to prepare mica flakes-coated rutile-type titania pearlescent pigment with urea as a precipitant. $TiO_2$ particles exhibit a high reflection of lights and optical properties with chemical stabilities, so they are appropriate for coating on luminescent pigments (mica). The coating principle of mi ca coated titania with various thicknesses was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tested by spectrophotometer. Mica with a particle size in the range of $40-60{\mu}m$ was suspended in water, and metal sulphates and urea were added to the mixture, which was heated to boiling. The change in pH was continuously followed. The metal oxide and crystal structure were affected by the conditions of $TiOSO_4$ concentration and reaction time with a sintering temperature the range of $800-1100^{\circ}C$.

• Membrane and Water Treatment
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• v.10 no.3
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• pp.223-229
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• 2019

Titania modified by 2-ethylimidazole (2-EI) (denoted as $2-EI-TiO_2$) demonstrated visible light photocatalytic activity for the degradation of organic compounds. $2-EI-TiO_2$ was a bright brown powder that exhibited similar crystallinity and morphology with the control $TiO_2$. A diffuse reflectance spectrum indicated that $2-EI-TiO_2$ absorbs visible light of all wavelengths. X-ray photoelectron spectroscopy (XPS) confirmed the cationic state of nitrogen species (e.g. Ti-O-N) on the surface of $2-EI-TiO_2$. Visible light-illuminated $2-EI-TiO_2$ degraded $10{\mu}M$ 4-chlorophenol (4-CP) by approximately 85% in 4 h. The photochemical activity of $2-EI-TiO_2$ was selective in targeting the organic compound. The repeated use of $2-EI-TiO_2$ decreased the photocatalytic activity for the 4-CP degradation. Experiments using radical scavengers and oxidant probes revealed that the oxidation by photogenerated holes is responsible for the degradation of organic compounds by illuminated $2-EI-TiO_2$ and the role of $^{\bullet}OH$ is negligible.