Journal of Powder Materials

In-Chul Yeo

4 Articles

Preparation of WO₃-TiO₂ Photocatalyst and Evaluation of Its Photo-activity in the Visible Light Range: In-Chul Yeo, In-Cheol Kang; J Powder Mater. 2013;20(6):474-478.; DOI: https://doi.org/10.4150/KPMI.2013.20.6.474

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The most general photocatalyst, TiO_2 and WO_3, are acknowledged to be ineffective in range of visible light. Therefore, many efforts have been directed at improving their activity such as: band-gap narrowing with non-metal element doping and making composites with high specific surface area to effectively separate electrons and holes. In this paper, the method was introduced to prepare a photo-active catalyst to visible irradiation by making a mixture with TiO_2 and WO_3. In the TiO_2-WO_3 composite, WO_3 absorbs visible light creating excited electrons and holes while some of the excited electrons move to TiO_2 and the holes remain in WO_3. This charge separation reduces electron-hole recombination resulting in an enhancement of photocatalytic activity. Added Ag plays the role of electron acceptor, retarding the recombination rate of excited electrons and holes. In making a mixture of TiO_2-WO_3 composite, the mixing route affects the photocatalytic activity. The planetary ball-mill method is more effective than magnetic stirring route, owing to a more effective dispersion of aggregated powders. The volume ratio of TiO_2(4) and WO_3(6) shows the most effective photocatalytic activity in the range of visible light in the view point of effective separation of electrons and holes.

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Photocatalytic activity of rutile TiO2 powders coupled with anatase TiO2 nanoparticles using surfactant
Jong Min Byun, Chun Woong Park, Young In Kim, Young Do Kim
journal of Korean Powder Metallurgy Institute.2018; 25(3): 257. CrossRef
Synthesis and Characterization of TiO2/CuS Nanocomposite Fibers as a Visible Light-Driven Photocatalyst
HyeLan An, Leeseung Kang, Hyo-Jin Ahn, Yong-Ho Choa, Chan Gi Lee
Journal of the Korean Ceramic Society.2018; 55(3): 267. CrossRef

A Study of Mechanical Properties and Microstructure of ZrO₂-Ag Depending on the Composite Route: In-Chul Yeo, Jae-Kil Han, In-Cheol Kang; J Korean Powder Metall Inst. 2012;19(6):416-423.; DOI: https://doi.org/10.4150/KPMI.2012.19.6.416

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Abstract PDF: This paper introduces an effect of a preparing ZrO_2-Ag composite on its mechanical properties and microstructure. In present study, ZrO_2-Ag was prepared by reduction-deposition route and wetting dispersive milling method, respectively. Two type of Ag powders (nano Ag and micron Ag size, respectively) were dispersed into ZrO_2 powder during wetting dispersive milling in D.I. water. Each sample was sintered at 1450°C for 2hr in atmosphere, and then several mechanical tests and analysis of microstructure were carried out by bending test, hardness, fracture toughness and fracture surface microstructure. As for microstructure, the Ag coated ZrO_2 showed homogeneously dispersed Ag in ZrO_2 in where pore defect did not appear. However, ZrO_2-nano Ag and ZrO_2-micro Ag composite appeared Ag aggregation and its pore defect, which carried out low mechanical property and wide error function value.

Investigation About Surface Microstructure of Aluminum with Change of Voltage, a Period of Treatment and Density of Electrolyte in Micro-Arc Oxidation Treatment: In-Chul Yeo, In-Cheol Kang; J Korean Powder Metall Inst. 2011;18(6):575-582.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.575

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MAO(Micro-Arc Oxidation) method was used to make Al_2O_3 surface on 6063 Al specimen. This study was focused on an influence of voltage, density of electrolyte and a period of treatment on the change of surface microstructure by using SEM(Scanning Electron Microscope), EDS(Energy Dispersive X-ray Spectroscopy). The microstructure shows higher roughness and thicker oxidized layer with increase of voltage and maintaining period of treatment. The density of electrolyte affected a formation of more dense surface and increase of a oxidized layer.

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Control of Nano-Scaled Surface Microstructure of Al Sample for Improving Heat Release Ability
In-Chul Yeo, In-Cheol Kang
Journal of Korean Powder Metallurgy Institute.2015; 22(1): 21. CrossRef
Influence of MAO Conditions on TiO2Microstructure and Its Photocatalytic Activity
Jeong-Gon Kim, In-Cheol Kang
Journal of Korean Powder Metallurgy Institute.2012; 19(3): 196. CrossRef

Preparation of C Doped TiO₂ Photocatalyst Activating to Visible Irradiation and Investigation of Its Photocatalytic Activity: In-Chul Yeo, In-Cheol Kang; J Korean Powder Metall Inst. 2010;17(4):281-288.; DOI: https://doi.org/10.4150/KPMI.2010.17.4.281

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Abstract PDF: A carbon doped TiO_2 (C-TiO_2) photocatalyst, which shows good photocatalytic activity to Ultraviolet irradiation and visible irradiation, was successfully prepared by co-grinding of TiO_2 with ethanol or Activated Carbon(C), followed by heat treatment at 200°C in air for 60 min. Ethanol and C were used as a representative agent of liquid and solid for carbon doping. Their influence on improving photocatalytic ability and carbon doping degree was studied with degradation of methyl orange and XPS analysis. The product prepared by co-grinding of TiO_2 with Ethanol had Ti-C and C-O chemical bonds and showed higher photocatalytic activity than the product prepared by co-grinding of TiO_2 with C, where just C-O chemical bond existed. As a result, mechanochemical route is useful to prepare a carbon doped TiO_2 photocatalyst activating to visible irradiation, where the solid-liquid operation is more effective than solid-solid operation to obtain a carbon doped TiO_2.

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