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Preparation and Characterization of Ag-TiO₂ Core-Shell-Type Nanoparticles
Kim, Young Hwan,Kang, Young Soo,Jo, Beong Gi 한국공업화학회 2004 Journal of Industrial and Engineering Chemistry Vol.10 No.5
Ag nanoparticles were synthesized by thermal decompositon of an Ag-oleate complex by using an electric furnace (autoclave) at 300℃ for 4 hrs. The particles were characterized by using a UV-vis spectrophotometer, a transmission electron microscope (TEM), and an X-ray powder diffractometer (XRD). The synthesized Ag nanoparticles were used as seeds for Ag-TiO₂ nanoparticles, which had core-shell structures. TEM images of the Ag-TiO₂ nanoparticles showed that the silver core was coated with titanium oxide. Ag-TiO₂ nanoparticles composed of a silver core (20-㎚ diameter) coated with titanium dioxide (less than 5 nm layer) were produced by a sol-gel process.
Park, Ok Kyung,Kang, Young Soo,Jo, Beong Gi 한국공업화학회 2004 Journal of Industrial and Engineering Chemistry Vol.10 No.5
For its use as an absorber of UV light in cosmetic products, TiO₂ was coated a with a SiO₂ layer to suppress its photocatalytic activity and to increase its dispersion ability. Silica-coated TiO₂ nanoparticles were prepared by a sol-gel process. High-resolution transmission electron microscopy (HRTEM) and X-ray photo-electron spectroscopy (XPS) analyses showed that hydrous silica was coated evenly on the surface of the TiO₂ particles. The effect of heat-treatment on the products, i.e., increasing annealing time and temperature, was followed by X-ray powder diffraction (XRD) spectroscopy. To study the suppression of the photocatalytic effect, an organic compound was added to the silica-coated TiO₂ sol and the solution was irradiated with UV light. The decrease in the photocatalytic activity and the UV shielding effect of the silica-coated TiO₂ nanoparticles were confirmed by recording UV-vis spectra, which showed more than an 80% decrease in the photocatalytic effect. Improved dispersion of the silica-coated TiO₂ nanoparticles, as compared with that of pure TiO₂, was verified by the increased Zeta potential value, from -22 ζ/㎷ for pure TiO₂ to -47 ζ/㎷ for the silica-coated TiO₂, at pH 7 as measured using a Zeta potential analyzer.
Synthesis of Cu Nanoparticles Prepared by Using Thermal Decomposition of Cu-oleate Complex
Kim, Young Hwan,Kang, Young Soo,Lee, Won Jae,Jo, Beong Gi,Jeong, Jee Hean TaylorFrancis 2006 Molecular Crystals and Liquid Crystals Vol.445 No.1
<P>In order to obtain well-dispersed Cu nanoparticles, we synthesized Cu nanoparticles by using thermal decomposition of Cu-oleate complex, which was prepared by the reaction with CuCl 2 and sodium oleate in aqueous condition. The resulting well-dispersed Cu nanoparticles were synthesized by autoclave. TEM image showed well-dispersed Cu nanoparticles with diameter of 8.9±1.3 nm. EDX spectrum and XRD peaks of the nanoparticles showed the highly crystalline nature of the Cu structures. The decomposition of Cu-oleate complex was analyzed with TGA and the crystallization of Cu nanoparticles was observed with XRD. UV-Vis absorption spectrum of Cu nanoparticles is also observed.</P>
Preparation and Antibiotic Property of Ag-SiO2 Nanoparticle
Kim, Young Hwan,Lee, Don Keun,Kim, Chang Woo,Cha, Hyun Gil,Kang, Young Soo,Jo, Beong Gi,Jeong, Jee Hean TaylorFrancis 2007 Molecular Crystals and Liquid Crystals Vol.464 No.1
<P> Silica particle was deposited with Ag nanoparticles to achieve hybrid structure. First, silica nanoparticles were synthesized according to the well-known Stöber method by hydrolysis and condensation of TEOS in a mixture of ethanol with water, using ammonia as catalyst to initiate the reaction. These SiO2 nanoparticles were dried at 100°C. We measured the size of these nanoparticles with transmission electron microscopy (TEM). Second, Ag-SiO2 nanoparticles were synthesized by reaction with AgNO3 and SiO2 nanoparticles at room temperature for 12 hrs. Results show silica nanoparticles of about 110 nm size deposited with Ag nanoparticles. Ag-SiO2 nanoparticles were investigated with TEM images, energy dispersive X-ray analysis (EDX) spectrum. The antibiotic property was examined with disk plate method.</P>