Journal of Powder Materials

[Korean]
Evaluation of TiO₂ Photocatalytic Activity with Addition of Carbon Nanotube: In-Chul Yeo, In-Cheol Kang; J Korean Powder Metall Inst. 2016;23(6):458-465. Published online December 1, 2016; DOI: https://doi.org/10.4150/KPMI.2016.23.6.458

248 View
1 Download

Abstract PDF: A TiO₂/CNT nanohybrid photocatalyst is synthesized via sol-gel route, with titanium (IV) isopropoxide and multi-walled carbon nanotubes (MWCNTs) as the starting materials. The microstructures and phase constitution of the nanohybrid TiO₂/CNT (0.005wt%) samples after calcination at 450°C, 550°C and 650°C in air are compared with those of pure TiO₂ using field-emission scanning electron microscopy and X-ray diffraction, respectively. In addition, the photocatalytic activity of the nanohybrid is compared with that of pure TiO₂ with regard to the degradation of methyl orange under visible light irradiation. The TiO₂/CNT composite exhibits a fast grain growth and phase transformation during calcination. The nanocomposite shows enhanced photocatalytic activity under visible light irradiation in comparison to pure TiO₂ owing to not only better adsorption capability of CNT but also effective electron transfer between TiO₂ and CNTs. However, the high calcination temperature of 650°C, regardless of addition of CNT, causes a decrease in photocatalytic activity because of grain growth and phase transformation to rutile. These results such as fast phase transformation to rutile and effective electron transfer are related to carbon doping into TiO₂.

[Korean]
Control of Nano-Scaled Surface Microstructure of Al Sample for Improving Heat Release Ability: In-Chul Yeo, In-Cheol Kang; J Korean Powder Metall Inst. 2015;22(1):21-26. Published online February 1, 2015; DOI: https://doi.org/10.4150/KPMI.2015.22.1.21

219 View
1 Download
2 Citations

In this study, the control of microstructure for increasing surface roughness of Al with an electro-chemical reaction and a post treatment is systematically investigated. The Al specimen is electro-chemically treated in an electrolyte. In condition of the post treatment at 100°C for 10 min, a change of the surface microstructure occur at 50V (5 min), and a oxidized layer is at 400V, to which lead a decreasing surface roughness. The minimum temperature of the post treatment for a change of microstructure is 80°C. Moreover, in the condition of 300V (5 min), the electro-chemical reaction is followed by the post treatment at 100°C, the critical enduring time for the change of microstructure is 3 min. The longer post treatment time leads to the rougher surface. The treated Al specimen demonstrate better heat release ability owing to the higher surface roughness than the non-treated Al.

Citations

Citations to this article as recorded by

Measurement of the Thermal Conductivity of a Polycrystalline Diamond Thin Film via Light Source Thermal Analysis
Hojun Kim, Daeyoon Kim, Nagyeong Lee, Yurim Lee, Kwangbae Kim, Ohsung Song
Korean Journal of Materials Research.2021; 31(12): 665. CrossRef
Effect of Tin Addition on the Melting Temperatures and Mechanical Properties of Al-Si-Cu Brazing Filler Metals
Min Sang Kim, Chun Woong Park, Jong Min Byun, Young Do Kim
Korean Journal of Materials Research.2016; 26(7): 376. CrossRef

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

208 View
0 Download
3 Citations

Abstract PDF

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.

Citations

Citations to this article as recorded by

Dual‐Function Nanocomposites: CuS@ZnO P–N Heterojunctions for Enhanced Light‐Driven Photocatalysis and Microbial Inactivation
Zahid Mahmood, Naseem Abbas, Muhammad Bilal, Khalid Javed, Sajid Mahmood, Shahid Iqbal, Mazloom Shah, Khalid M. Alotaibi
Microscopy Research and Technique.2025; 88(6): 1881. CrossRef
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

[Korean]
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

111 View
0 Download

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.

[Korean]
Influence of MAO Conditions on TiO₂ Microstructure and Its Photocatalytic Activity: Jeong-Gon Kim, In-Cheol Kang; J Korean Powder Metall Inst. 2012;19(3):196-203.; DOI: https://doi.org/10.4150/KPMI.2012.19.3.196

315 View
0 Download
2 Citations

Abstract PDF

TiO_2 was successfully formed on a Ti specimen by MAO (Micro-Arc-Oxidation) method treated in Na_3PO_4 electrolyte. This study deals with the influence of voltage and working time on the change of surface microstructure and phase composition. Voltage affected the forming rate of the oxidized layer and surface microstructure where, a low voltage led to a high surface roughness, more holes and a thin oxidized layer. On the other hand, a high voltage led to more dense surface structure, wider surface holes, a thick layer and fewer holes. Higher voltage increases photocatalytic activity because of better crystallization of the oxidized layer and good phase composition with anatase and rutile TiO_2, which is able to effectively separate excited electrons and holes at the surface.

Citations

Citations to this article as recorded by

Study on thermal behavior of Ammonium Hexafluofide Titanate for Synthesis of TiO2 Powders
Duk-Hee Lee, Jae-Ryang Park, Chan-Gi Lee, Kyung-Soo Park, Hyeon-Mo Kim
Journal of Korean Powder Metallurgy Institute.2016; 23(5): 353. CrossRef
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

[Korean]
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

278 View
0 Download
2 Citations

Abstract PDF

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.

Citations

Citations to this article as recorded by

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

[Korean]
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

188 View
0 Download

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.

[Korean]
The Relation Between a Visible-light Photocatalytic Activity of TiO_2-xN_x and NH₃ Amount/the Period of Grinding Time: In-Cheol Kang, Jun-Bin Ko, Jae-Kil Han, Kwang-Hee Kim, Sung-Chang Choi; J Korean Powder Metall Inst. 2009;16(3):196-202.; DOI: https://doi.org/10.4150/KPMI.2009.16.3.196

289 View
0 Download

Abstract PDF: A visible-light photoactive TiO_2-xN_x photocatalyst was synthesized successfully by means of cogrinding of anatase-TiO_2(a-TiO_2) in NH_3 ambient, followed by heat-treatment at 200°C in air environment. In general, it is well known that the grinding-operation induces phase transformation of a-TiO_2 to rutile TiO_2. This study investigates the influence of the amount of NH_3 gas on the phase transformation rate of a-TiO_2 and enhancement of visible-light photocatalytic activity, and also examines the relation between the photocatalytic activity and the period of grinding time. The phase transformation rate of a-TiO_2 to rutile is retarded with the amount of NH3 injected. And the visible-light photocatalytic activity of samples, was more closely related to the period of grinding time than NH_3 amount injected, which means that the doping amount of nitrogen into TiO_2 more effective to mechanical energy than NH_3 amount injected. XRD, XPS, FT-IR, UV-vis, Specific surface area (SSA), NOx decomposition techniques are employed to verify above results more clearly.

Search