Papers by Author: Young Soo Kang

Abstract: In the past decades, porous materials have attracted great scientific and industrial interest due to their appealing structures and potential applications in separation, purification, catalysis, devices, and so forth. The developing community of ordered mesoporous materials has carried on this exploration of the mesoscopical territory, which promises their unique capacities related to large molecules and their transportation in confined space. Thus rational control and adjustment of pores have been continually focused during the synthesis of ordered mesoporous materials with diverse intrinsic properties. In this work, vitamin C encapsulated mesoporous silica was successfully synthesized with tetraethylorthosilicate (TEOS). TEOS was subjected to sol-gel process in the presence of cetyltrimethylammonium bromide (CTAB). The composition and size of mesoporous silica was controlled by fitting the molar ratio of starting materials. The mesoporous silica can be applied to the field of the cosmetics and bio-medicine as drug delivery.

Abstract: The magnetic Co nanoparticle was prepared by coprecipitation route in aqueous solution and Figlarz’s polyol method which consists of refluxing a solution of the metal precursor in polyol. As the former method, the Co nanoparticle was synthesized by reduction of cobalt chloride with sodium borohydride in aqueous solution. And the latter method, the polyol method can be applied to the production of Co nanoparticle by reducing cobalt chloride and cobalt acetate with polyol such as ethylene glycol, trimethylene glycol. The size of nanoparticle was confirmed by transmission electron microscopy images and scanning electron microscopy images, according to the different methods The crystal structure of nanoparticle according to reaction condition was characterized by X-ray diffraction data. The magnetic properties were characterized with saturation magnetization from hysteresis loop by vibrating sample magnetometer (VSM).

Abstract: Nd-Fe-B nanoparticles was prepared by coprecipitation method in aqueous solution. The parameters for the composition are the concentration of borohydride solution and the pH of the solution containing metal ion. The B and Nd contents were found to vary with pH and borohydride concentration. The crystal structure of the synthesized nanoparticles was identified with X-ray powder diffraction (XRD). The size and shape of nanoparticles were confirmed by transmission electron microscope (TEM). The magnetization curves of nanoparticles and nanocomposite were characterized with vibrating sample magnetometer (VSM). Energy dispersive X-ray spectrometer (EDS) was used to characterize composition of Nd-Fe-B nanoparticles.

Abstract: A room temperature route for doping silica particles with Cu nanoparticles to achieve hybrid structures is introduced. 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 nanoaprticles were dried at 100 oC. We measured the size of these nanoparticles with transmission electron microscopy (TEM). Second, Cu-SiO2 nanoparticles were synthesized by reaction with CuCl2 and SiO2 nanoparticles in presence of catalyst at room temperature for 12 hrs. Results show silica nanoparticles of about 70 nm size with regularly deposited Cu nanoparticles. Cu-SiO2 nanoparticles were investigated with TEM images, energy dispersive X-ray analysis (EDX) spectrum and so on.

Abstract: The monodispersed zinc oxide nanowires with lateral dimensions as thin as 20 nm and lengths up to 2 μm have been synthesized in a simple organic solution by using hydrothermal method. Particularly, these zinc oxide nanostructures has been prepared into single-crystalline prisms or belts with uniform diameters along the entire length. The structure and characteristic of the as-obtained ZnO nanostructures were confirmed by XRD, TEM, HRTEM, and EDX. UV measurements and photoluminescence had been used to characterize the optical properties and confirm the crystal perfection of these ZnO nanomaterials.

Abstract: Nanoparticles of anatase TiO2 doped with 2 at.% Sc3+ and 2 at.% V5+ ions were synthesized by sol-gel method. Average crystal sizes of TiO2, TiO2+2 at.% Sc, TiO2+2 at.% V and TiO2+2 at.% (Sc+V) calculated from XRD patterns are 18.0, 16.9, 18.0, 16.2 nm, respectively. HRTEM images of TiO2 and TiO2+2 at.% (Sc+V) exhibit well-defined lattice fringe. The lattice spacings of TiO2 and TiO2+2 at.% (Sc+V) are both measured to be 3.3 Å, which correspond to the distance between the (101) planes of anatase TiO2. Raman spectra of the samples demonstrate the well dispersion of Sc3+ and V5+ ions in the TiO2 matrix. UV-vis diffuse reflectance absorption spectra of the samples show the characteristics of TiO2, and the diffuse reflectance spectra of TiO2+2 at.% V and TiO2+2 at.% (Sc+V) exhibit red shifts and weak wide absorptions in the visible region of 400-600 nm.

Abstract: Core/shell structured TiO2/ZnO was synthesized in a basic aqueous solution through a simple hydrolyzing method. The powder X-ray diffraction (XRD) and transmission electron microscopy of the initial TiO2/ZnO powder showed diffraction peaks corresponding to the ZnO and TiO2 phase. The structure and thickness of ZnO shell (about 2.5 nm) coated TiO2 surface as thin layers or nanoclusters, depends upon the reactant concentration and the reaction time. The characteristics of the optical absorption were described by UV-visible absorption spectroscopy.

Abstract: The magnetic α-Fe nanoparticles were carried out using two-preparation methods that include solution phase metal salt reduction and organometallic precursor decomposition. Under the different reaction conditions such as precursor and reaction time, the magnetic properties of α-Fe nanoparticles were studied. The size of nanoparticle was confirmed by transmission electron microscope (TEM) images. The magnetic properties were characterized with saturation magnetization(Ms) from hysteresis loop by vibrating sample magnetometer (VSM). The crystallinity and structure of α-Fe nanoparticles was investigated by X-ray diffraction (XRD).