• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.54-54
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• 2010

Zinc oxide is metal oxide semiconductor with the 3.37 eV bandgap energy. Zinc oxide is very attractive materials for many application fields. Zinc Oxide has many advantages such as high conductivity and good transmittance in visible region. Also it is cheaper than other semiconductor materials such as indium tin oxide (ITO). Therefore, ZnO is alternative material for ITO. ZnO is attracting attention for its application to transparent conductive oxide (TCO) films, surface acoustic wave (SAW), films bulk acoustic resonator (FBAR), piezoelectric materials, gas-sensing, solar cells and photocatalyst. In this study, we synthesized ZnO nanoparticles and defined their physical and chemical properties. Also we studied about the application of ZnO nanoparticles as a photocatalyst and try to find a enhancement photocatalytic activity of ZnO nanorticles.. We synthesized ZnO nanoparticles using spray-pyrolysis method and defined the physical and optical properties of ZnO nanoparticles in experiment I. When the ZnO are exposed to UV light, reduction and oxidation(REDOX) reaction will occur on the ZnO surface and generate ${O_2}^-$ and OH radicals. These powerful oxidizing agents are proven to be effective in decomposition of the harmful organic materials and convert them into $CO_2$ and $H_2O$. Therefore, we investigated that the photocatalytic activity was increased through the surface modification of synthesized ZnO nanoparticles. In experiment II, we studied on the stability of ZnO nanoparticles in water. It is well known that ZnO is unstable in water in comparison with $TiO_2$. $Zn(OH)_2$ was formed at the ZnO surface and ZnO become inactive as a photocatalyst when ZnO is present in the solution. Therefore, we prepared synthesized ZnO nanoparticles that were immersed in the water and dried in the oven. After that, we measured photocatalytic activities of prepared samples and find the cause of their photocatalytic activity changes.

• Journal of Integrative Natural Science
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• v.8 no.1
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• pp.67-74
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• 2015

Sensing characteristics for porous smart particle based on DBR smart particles were reported. Optically encoded porous silicon smart particles were successfully fabricated from the free-standing porous silicon thin films using ultrasono-method. DBR PSi was prepared by an electrochemical etch of heavily doped $p^{++}$-type silicon wafer. DBR PSi was prepared by using a periodic pseudo-square wave current. The surface-modified DBR PSi was prepared by either thermal oxidation or thermal hydrosilylation. Free-standing DBR PSi films were generated by lift-off from the silicon wafer substrate using an electropolishing current. Free-standing DBR PSi films were ultrasonicated to create DBR-structured porous smart particles. Three different surface-modified DBR smart particles have been prepared and used for sensing volatile organic vapors. For different types of surface-modified DBR smart particles, the shift of reflectivity mainly depends on the vapor pressure of analyte even though the surfaces of DBR smart particles are different. However huge difference in the shift of reflectivity depending on the different types of surface-modified DBR smart particles was obtained when the vapor pressures are quite similar which demonstrate a possible sensing application to specify the volatile organic vapors.

• Journal of Microbiology and Biotechnology
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• v.19 no.9
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• pp.904-910
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• 2009

The development of effective cellular imaging requires a specific labeling method for targeting, tracking, and monitoring cellular/molecular events in the living organism. For this purpose, we studied the cellular uptake of isocyanide-functionalized silver and gold nanoparticles by surface-enhanced Raman scattering (SERS). Inside a single mammalian cell, we could monitor the intracellular behavior of such nanoparticles by measuring the SERS spectra. The NC stretching band appeared clearly at ${\sim}2,100cm^{-1}$ in the well-isolated spectral region from many organic constituents between 300 and 1,700 or 2,800 and $3,600cm^{-1}$. The SERS marker band at ${\sim}2,100cm^{-1}$ could be used to judge the location of the isocyanide-functionalized nanoparticles inside the cell without much spectral interference from other cellular constituents. Our results demonstrate that isocyanide-modified silver or gold nanoparticle-based SERS may have high potential for monitoring and imaging the biological processes at the single cell level.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.105-107
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• 2002

The device characteristics and the interface electronic structures of organic light-emitting devices based on tris-(8-hydroxyquinoline)aluminum were investigated with $Al/CaF_2$, Al/LiF, and Al-only cathodes. Similar to the Al/LiF cathode, the $Al/CaF_2$ cathode greatly improved the performance of the device over Al-only cathode. However, a photoelectron spectroscopy study revealed that despite the performance improvement, the evolution of the new peaks during $Al/CaF_2$ cathode formation closely resembled those of the Al-only cathode rather than the Al/LiF cathode.

• Applied Chemistry for Engineering
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• v.31 no.1
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• pp.67-72
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• 2020

Biomaterials are frequently functionalized with Arg-Gly-Asp (RGD) peptides to provide cell adhesion sites. In this study, RGD peptides were enzymatically coupled on to the surface of fibroin microspheres. Papain exhibited a strong preference for dansyl phenylalanine for the peptide formation with fibroin microspheres. Thus, RGD1 peptide was designed to carry cysteine to both sides of the sequence, glycine as a spacer and two residues of phenylalanine at the C-terminal (CRGDCGFF). The enzymatic modification facilitated by an increasing amount of substrate and by the presence of organic solvent, dimethylsulfoxide at 25% (v/v). Microspheres coupled with RGD1, showed a significantly different precipitation property and an increased apparent volume, possibly due to the steric hindrance of RGD peptides on the surface. Transmission electron microscopy also confirmed the presence of cysteine residues in RGD1 coupled on the surface of microspheres stained with gold nanoparticles. RGD1-microspheres significantly facilitated the growth of murine fibroblast 3T3 cells even under non-adhesion culture conditions.

• Environmental Engineering Research
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• v.20 no.3
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• pp.205-211
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• 2015

Reduced forms of iron, such as zero-valent ion (ZVI) and ferrous ion (Fe[II]), can activate dissolved oxygen in water into reactive oxidants capable of oxidative water treatment. The corrosion of ZVI (or the oxidation of (Fe[II]) forms a hydrogen peroxide ($H_2O_2$) intermediate and the subsequent Fenton reaction generates reactive oxidants such as hydroxyl radical ($^{\bullet}OH$) and ferryl ion (Fe[IV]). However, the production of reactive oxidants is limited by multiple factors that restrict the electron transfer from iron to oxygen or that lead the reaction of $H_2O_2$ to undesired pathways. Several efforts have been made to enhance the production of reactive oxidants by iron-induced oxygen activation, such as the use of iron-chelating agents, electron-shuttles, and surface modification on ZVI. This article reviews the chemistry of oxygen activation by ZVI and Fe(II) and its application in oxidative degradation of organic contaminants. Also discussed are the issues which require further investigation to better understand the chemistry and develop practical environmental technologies.

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2705-2710
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• 2011

Four MOFs functionalized with 1-Me, 1-Pr, 1-Ph, and 1-$PhCF_3$ were prepared through post-synthetic modifications of a metal-organic framework (MOF), UMCM-1-$NH_2$ (1) with acetic, butyric, benzoic, and 4-(trifluoromethyl)benzoic anhydrides, respectively. Methane adsorption measurements between 253 and 298 K at pressures up to 1 bar indicated that both 1-Ph and 1-$PhCF_3$ adsorbed more $CH_4$ than the parent MOF, 1. All the functionalized MOFs adsorbed more $CO_2$ than 1 under conditions similar to the $CH_4$ test. The introduction of functional groups promoted adsorption of both $CH_4$ and $CO_2$ despite significantly reducing Brunauer-Emmet-Teller (BET) surface area: 4170 (1), 3550 (1-Me), 2900 (1-Pr), 3680 (1-Ph), and 3520 $m^2/g$ (1-$PhCF_3$). Electron-withdrawing aromatic groups (1-Ph, 1-$PhCF_3$) more effectively enhanced $CO_2$ adsorption than electron-donating alkyl groups (1-Me, 1-Pr). In particular, 1-Ph adsorbed 23% more $CO_2$ at 298 K and 50% more at 253 K than 1.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1128-1134
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• 2012

We investigated a new method for patterning organic field-effect transistors (OFETs) using a photopatternable conducting polymer nanocomposite, consisting of poly(3-hexylthiophene) (P3HT)-coated gold nanoparticles (AuNPs) that had been modified with a photoreactive cinnamate group, to form P3HT-AuNP-CI. We found that the addition of the cinnamate group to the nanoparticle surface assisted the preparation of a solvent-resistive semiconducting film and preserved the P3HT ordering, which was interrupted by Au-P3HT interactions, as well as provided UV-controllable electrical properties. The P3HT-AuNPs-CI films could be microscale-patterned via a UV crosslinking photoreaction, represented as a promising photopatternable semiconductor material for use in advanced applications, with tunable electrical properties for fabrication of sub-micron and microscale electronic devices.

• Applied Chemistry for Engineering
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• v.35 no.4
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• pp.346-351
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• 2024

Chemical reduction using catalysts and NaBH₄ presents a promising approach for reducing 4-nitrophenol contamination while generating valuable byproducts. Covalent organic frameworks (COFs) emerge as a versatile platform for supporting catalysts due to their unique properties, such as high surface area and tunable pore structures. This study employs design of experiments (DOE) to systematically optimize the synthesis of Cu embedded COF (Cu/COF) catalysts for the reduction of 4-nitrophenol. Through a series of experimental designs, including definitive screening, mixture method, and central composition design, the main synthesis parameters influencing Cu/COF formation are identified and optimized: MEL:TPA:DMSO = 0.31:0.36:0.33. Furthermore, the optimal synthesis temperature and time were predicted to be 195 ℃ and 14.7 h. Statistical analyses reveal significant factors affecting Cu/COF synthesis, facilitating the development of tailored nanostructures with enhanced catalytic performance. The catalytic efficacy of the optimized Cu/COF materials is evaluated in the reduction of 4-nitrophenol, demonstrating promising results in line with the predictions from DOE.

• Applied Chemistry for Engineering
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• v.33 no.3
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• pp.296-301
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• 2022

Due to the fact that zirconium based metal-organic frameworks (Zr-MOFs), such as UiO-66, have a large specific surface area and excellent selective adsorption capacity, Zr-MOFs are gaining attention as materials that can provide protection from the attack of chemical warfare agents in battleground. However, most of the metal-organic frameworks have an issue of selective adsorption capacity degraded by water molecules when exposed to the atmosphere, because of the weak metal-organic ligand bonds and the presence of voids. Therefore, polydimethylsiloxane (PDMS), a representative hydrophobic polymer material, was coated on the surface of UiO-66 to enhance the sustainability of the diisopropyl methylphosphonate (DIMP) sorption capacity in the battleground condition. Through the analysis of surface structure and organic functional group distribution of PDMS coated UiO-66, silicon was confirmed to be evenly coated. The contact angle increased by over 30° for the PDMS coated UiO-66, indicating that the hydrophobicity was improved. In addition, both the UiO-66 and PDMS coated UiO-66 were used as adsorbents for DIMP, a similar chemical warfare agent, to investigate the durability of adsorption capacity in a high humidity environment. The PDMS coated UiO-66 showed higher durability of adsorption capacity for 20 days than that of pristine UiO-66.