• Applied Chemistry for Engineering
• /
• v.18 no.5
• /
• pp.467-474
• /
• 2007

The palladium and gold nanoparticles containing PAN-based active carbon fiber (ACF) with a high specific surface area were prepared. Using the BET, TEM, FE-SEM, and XPS, their specific surface area and pore volume, pore structure, and the change in surface oxygen groups with time were analyzed and $SO_2$ adsorption performances were investigated. Because of the impregnating process, the micropore volume was mostly decreased from 95.5% to 30.5~43.7% compared with the total pore volume. And the change in surface oxygen groups with time was higher for the metal salt than the nanoparticles. Also, $SO_2$ breakthrough time of PAN-ACFs impregnated with Au nanoparticles and metal salts did not change compared with that of the non-impregnated PAN-ACF. But the PAN-ACF impregnated with Pd nanoparticles (100 ppm) showed good $SO_2$ adsorption performance as the breakthrough time of 880 sec. These results indicated that the $SO_2$ adsorption performance depended on the change in surface oxygen groups with time and the moderate impregnation of Pd nanoparticles on the PAN-ACF caused the increase in the $SO_2$ adsorption performance by a catalytic action.

• Journal of the Korean Applied Science and Technology
• /
• v.35 no.4
• /
• pp.1197-1205
• /
• 2018

UV protection cosmetics belong to functional cosmetics and contain organic or inorganic UV blocking pigments. The inorganic UV blocking pigments are mainly zinc oxide and titanium dioxide. It is known that inorganic UV blocking pigment has a diameter of 60 to 100 nm and has good blocking ability of UVA and UVB. Also, it has high inactivity against sunlight including UV and is excellent in safety. In addition, it is not absorbed or accumulated on the skin like organic pigments and does not cause skin irritation or allergy. In this study, mica, a plate-shaped inorganic pigment, nanosized titanium dioxide, an UV blocking material, and hydrophobic silica were surface-treated with surfactants. And then, titanium dioxide nanoparticles and silica were physically adsorbed on the mica by non-chemical mutual attraction due to differences in charge. Thereafter, the mica complex was surface-treated with silane to prepare a hydrophobic UV blocking pigment complex. The plate-shaped UV blocking composite improves the cohesiveness of a general nanoparticle material titanium dioxide, enhances UV blocking effect due to uniform dispersion, and can greatly improve dispersion stability in cosmetic formulations by surface treatment with hydrophobic property. The surface charge of the pigment was evaluated by zeta potential. The properties of the UV blocking pigment complex were evaluated by FE-SEM, XRD, FT-IR and UV-VIS.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.463-463
• /
• 2014

Dye-sensitized solar cells (DSSCs) have generated a strong interest in the development of solid-state devices owing to their low cost and simple preparation procedures. Effort has been devoted to the study of electrolytes that allow light-to-electrical power conversion for DSSC applications. Several attempts have been made to substitute the liquid electrolyte in the original solar cells by using (2,2',7,7'-tetrakis (N,N-di-p-methoxyphenylamine)-9-9'-spirobi-fluorene (spiro-OMeTAD) that act as hole conductor [1]. Although efficiencies above 3% have been reached by several groups, here the major challenging is limited photoelectrode thickness ($2{\mu}m$), which is very low due to electron diffusion length (Ln) for spiro-OMeTAD ($4.4{\mu}m$) [2]. In principle, the $TiO_2$ layer can be thicker than had been thought previously. This has important implications for the design of high-efficiency solid-state DSSCs. In the present study, we have fabricated 3-D Transparent Conducting Oxide (TCO) by growing tin-doped indium oxide (ITO) nanowire (NWs) arrays via a vapor transport method [3] and mesoporous $TiO_2$ nanoparticle (NP)-based photoelectrodes were prepared using doctor blade method. Finally optimized light-harvesting solid-state DSSCs is made using 3-D TCO where electron life time is controlled the recombination rate through fast charge collection and also ITO NWs length can be controlled in the range of over $2{\mu}m$ and has been characterized using field emission scanning electron microscopy (FE-SEM). Structural analyses by high-resolution transmission electron microscopy (HRTEM) and X-Ray diffraction (XRD) results reveal that the ITO NWs formed single crystal oriented [100] direction. Also to compare the charge collection properties of conventional NPs based solid-state DSSCs with ITO NWs based solid-state DSSCs, we have studied intensity modulated photovoltage spectroscopy (IMVS), intensity modulated photocurrent spectroscopy (IMPS) and transient open circuit voltages. As a result, above $4{\mu}m$ thick ITO NWs based photoelectrodes with Z907 dye shown the best performing device, exhibiting a short-circuit current density of 7.21 mA cm-2 under simulated solar emission of 100 mW cm-2 associated with an overall power conversion efficiency of 2.80 %. Finally, we achieved the efficiency of 7.5% by applying a CH3NH3PbI3 perovskite sensitizer.

• Journal of the Korean Magnetics Society
• /
• v.16 no.1
• /
• pp.102-106
• /
• 2006

Magnetic nanoparticles can be used for a variety of biomedical applications. They can be used in the targeted delivery of therapeutic agents in vivo, in the hyperthermic treatment of cancers. in magnetic resonance (MR) imaging as contrast agents and in the biomagnetic separations of biomolecules. We have synthesized magnetite $(Fe_3O_4)$ nanoparticles using chemical coprecipitation technique with sodium oleate as surfactant. Nanoparticle size can be varied from 2 to 8nm by controlling the sodium oleate concentration. Magnetite phase nanoparticles could be observed from X-ray diffraction. Magnetic colloid suspensions containing particles with sodium oleate and chitosan have been prepared. Nanoparticles, both oleate-coated and chitosan-coated, have been characterized by several techniques. Atomic farce microscope (AFM) was used to image the coated nanoparticles. Magnetic hysteresis measurement were performed using a superconducting quantum interference device (SQUID) magnetometer at room temperature to investigate the magnetic properties of the magnetite nanoparticles. The SQUID measurements revealed superparamagnetism of nanoparticles.

• Composites Research
• /
• v.35 no.3
• /
• pp.201-215
• /
• 2022

This paper presents the development of thin and lightweight ultra-high temperature radar-absorbing ceramic composites composed of an aluminosilicate ceramic matrix-based geopolymer reinforced ceramic fiber and sendust magnetic nanoparticles in X-band frequency range (8.2~12.4 GHz). The dielectric properties with regard to complex permittivity of ceramic/sendust-aluminosilicate composites were proportional to the size of sendust magnetic nanoparticle with high magnetic characteristic properties as flake shape and its concentrations in the target frequency range. The characteristic microstructures, element composition, phase identification, and thermal stability were examined by SEM, EDS, VSM and TGA, respectively. The fabricated total thicknesses of the proposed single slab ultra-high temperature radar absorber correspond to 1.585 mm, respectively, exhibiting their excellent EM absorption performance. The behavior of ultra-high temperature EM wave absorption properties was verified to the developed free-space measurement system linked with high temperature furnace for X-band from 25℃ to 1,000℃.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.15 no.1
• /
• pp.15-26
• /
• 2017

Cobalt ferrocyanide (CoFC) or nickel ferrocyanide (NiFC) magnetic nanoparticles (MNPs) were fabricated for efficient removal of radioactive cesium, followed by rapid magnetic separation of the absorbent from contaminated water. The $Fe_3O_4$ nanoparticles, synthesized using a co-precipitation method, were coated with succinic acid (SA) to immobilize the Co or Ni ions through metal coordination to carboxyl groups in the SA. CoFC or NiFC was subsequently formed on the surfaces of the MNPs as Co or Ni ions coordinated with the hexacyanoferrate ions. The CoFC-MNPs and NiFC-MNPs possess good saturation magnetization values ($43.2emu{\cdot}g^{-1}$ for the CoFC-MNPs, and $47.7emu{\cdot}g^{-1}$ for the NiFC-MNPs). The fabricated CoFC-MNPs and NiFC-MNPs were characterized by XRD, FT-IR, TEM, and DLS. The adsorption capability of the CoFC-MNPs and NiFC-MNPs in removing cesium ions from water was also investigated. Batch experiments revealed that the maximum adsorption capacity values were $15.63mg{\cdot}g^{-1}$ (CoFC-MNPs) and $12.11mg{\cdot}g^{-1}$ (NiFC-MNPs). Langmuir/Freundlich adsorption isotherm equations were used to fit the experimental data and evaluate the adsorption process. The CoFC-MNPs and NiFC-MNPs exhibited a removal efficiency exceeding 99.09% for radioactive cesium from $^{137}Cs$ solution ($18-21Bq{\cdot}g^{-1}$). The adsorbent selectively adsorbed $^{137}Cs$, even in the presence of competing cations.