• Bulletin of the Korean Chemical Society
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• 제34권2호
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• pp.374-378
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• 2013

Two novel binuclear metal-organic coordination complexes [$Cd_2(Hdpa)_4(bpy)_2$] (1), [$Dy_2(dpa)_2(bpy)_2(NO_3)_2-(H_2O)_2$](bpy) (2) (where $H_2dpa$ = biphenyl-2,2'-dicarboxylic acid, bpy = 2,2'-bipyridine) have been synthesized under hydrothermal conditions and characterized by single crystal X-ray diffraction, spectral method (IR), elemental analysis (EA), powder X-ray diffraction (XRD), electronic spectra (UV-vis), fluorescent in the solid state and thermogravimetric analysis (TGA). Complexes 1-2 crystallizes isomorphously in the Triclinic space group P-1. The ${\pi}-{\pi}$ stacking interactions and hydrogen-bonds play a vital role in determining the crystal packing and construction of the extended 3-D supramolecular network.

• Bulletin of the Korean Chemical Society
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• 제34권5호
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• pp.1481-1486
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• 2013

Bifunctional Fe-SBA-15-$SO_3H$ mesoporous materials with different Si/Fe molar ratios (3, 5, and 7) have been synthesized via a simple direct hydrothermal method and characterized by XRD, $N_2$-adsorption/desorption, TG/DTG and FT-IR techniques, and used as solid acid catalysts in the esterification of lactic acid with methanol. XRD and $N_2$ sorption characterizations show successful iron doping within the mesoporous channels of SBA-15-$SO_3H$. The FT-IR and TG/DTG characterizations also reveal the presence of iron. With the incorporation of Fe ions into the SBA-15-$SO_3H$, the acid sites substantially increased because of the self-separated acidity of the hydrolysis of $Fe^{3+}$ solutions. However, in the Si/Fe = 3 molar ratio, the catalytic conversion decreased which is caused by the reduced cooperation effect between the acid pairs due to the weakened hydrogen bonds and collapse of the pore structure. This further suggests that the mesoporous structure decreases with the decrease in Si/Fe ratio.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.44.2-44.2
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• 2009

BCP powder was synthesized using microwave hydrothermal process with mixed calcium hydroxide and phosphoric acid. After using replica method, porous BCP scaffold was fabricated. PU (Poly Urethane) was used as the fugitive skeleton to fabricate the porous scaffold. BCP powder was mixed in PVB (Polyvinyl butyral) and ethanol solution and then applied to the PU foam by dip coating. After several times of coating and the subsequent oven drying the coated PU foam was burnt out at $750^{\circ}C$ at air to remove the PU. The resulting networked porous composites were sintered at $1250^{\circ}C$, $1300^{\circ}C$ and $1350^{\circ}C$ in microwave furnace for 30 minutes. Material properties of the porous bodies like compressive strength and porosity were investigated. Detailed microstructure of the BCP porous body was characterized by SEM and XRD and TEM techniques. In our experiments, the relationship between mechanical property and viscosity of powder, sintering temperature was investigated.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.190-190
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• 2010

Zinc oxide is the most attractive material due to the large direct band gap (3.37 eV), excellent chemical and thermal stability, and large exciton binding energy (60 meV). Recently, ZnO nanorods were used as the high efficient antireflection coating layer of solar cells based on silicon (Si). In this reports, we studied the effects of rapid thermal annealing (RTA) treatment on optical properties of ZnO nanorods. For fabrication of ZnO nanorods, there are many methods such as hydrothermal method, sol-gel method, and metal organic chemical vapor deposition method. Among of them, we used the conventional wet chemical method which is simple and low temperature growth. In order to synthesize the ZnO nanorods, the ZnO films were deposited on Si substrate by RF magnetron sputtering at room temperature and the samples were dipped to aqua solution containing the zinc nitrate and hexamethylentetramines (HMT). The synthesis process was achieved in keeping with temperature of $90-95^{\circ}C$ and under constant stirring. The morphology of ZnO nanorods on glass and Si was characterized by scanning electron microscopy. For the analysis of antireflection performance, the reflectance and transmittance were measured by spectrophotometer. And for analyzing the effects of RTA treatment on ZnO nanorods, crystalline properties were investigated by X-ray diffraction measurements and optical properties was estimated by photoluminescence spectra.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2011년도 추계학술논문집 1부
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• pp.357-360
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• 2011

A new copper adenine MOF (Bio-MOF) was synthesized by hydrothermal procedure and explored for its low temperature $CO_2$ adsorption. In this adenine a DNA nucleotide was used as a ligand for Cu in DMF solution at $130^{\circ}C$. The synthesized Bio MOF was characterized by XRD, SEM, EDS, TG and BE Tresults. The material possesses high surface area (716.08 $m^2g^{-1}$) with mono dispersed particles of about 2.126 nm. The maximum $CO_2$ adsorption capacity is 5wt% at $50^{\circ}C$, which is regenerable at $100^{\circ}C$ which is very low when compared to other metal organic frame work studied. This study proves that the synthesized material is also be a choice materials for low temperature $CO_2$adsorption.

• 한국표면공학회지
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• 제52권5호
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• pp.258-264
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• 2019

Assembling heterostructures by combining dissimilar oxide semiconductors is a promising approach to enhance charge separation and transfer in photoelectrochemical (PEC) water splitting. In this work, the CuO nanorods array/$Cu_2O$ thin film bilayered heterostructure was successfully fabricated by a facile method that involved a direct electrodeposition of the $Cu_2O$ thin film onto the vertically oriented CuO nanorods array to serve as the photoelectrode for the PEC water oxidation. The resulting copper-oxide-based heterostructure photoelectrode exhibited an enhanced PEC performance compared to common copper-oxide-based photoelectrodes, indicating good charge separation and transfer efficiency due to the band structure realignment at the interface. The photocurrent density and the optimal photocurrent conversion efficiency obtained on the CuO nanorods/$Cu_2O$ thin film heterostructure were $0.59mA/cm^2$ and 1.10% at 1.06 V vs. RHE, respectively. These results provide a promising route to fabricating earth-abundant copper-oxide-based photoelectrode for visible-light-driven hydrogen generation using a facile, low-cost, and scalable approach of combining electrodeposition and hydrothermal synthesis.

• Nano
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• 제13권11호
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• pp.1850135.1-1850135.8
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• 2018

A one-step high-temperature solvothermal approach to the synthesis of monolayer or bilayer $MoS_2$ anchored onto reduced graphene oxide (RGO) sheet (denoted as $MoS_2/RGO$) is described. It was found that single-layered or double-layered $MoS_2$ were synthesized directly without an extra exfoliation step and well dispersed on the surface of crumpled RGO sheets with random orientation. The prepared $MoS_2/RGO$ composites delivered a high reversible capacity of $900mAhg^{-1}$ after 200 cycles at a current density of $200mAg^{-1}$ as well as good rate capability as anode active material for lithium ion batteries. This one-step high-temperature hydrothermal strategy provides a simple, cost-effective and eco-friendly way to the fabrication of exfoliated $MoS_2$ layers deposited onto RGO sheets.

• 한국습지학회지
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• 제21권2호
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• pp.152-156
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• 2019

본 연구는 수중 암모늄 이온을 처리하기 위하여 자성 제올라이트를 합성하여 흡착 특성을 평가하였다. 표면개질된 자성 제올라이트는 수열작용으로 합성되었다. 제올라이트와 $Fe_3O_4$ 복합체는 SEM과 XRD 분석 결과 혼합비 12.6% 범위이내에서 최적인 상태로 침투 혼합된 것으로 관찰되었다. 최적의 흡착 pH는 중성부근인 약 8근처에서 나타났고, 최대 흡착량은 $Fe_3O_4$ 함량의 증가에 따라 감소하였다. 수중 암모늄 이온은 Langmuir 식에 근사하는 흡착식으로 나타났다. 개발된 합성제올라이트 흡착제는 질소농도의 관리가 필요한 습지환경 보호에도 적용 가능할 것으로 판단된다.

• Journal of Electrochemical Science and Technology
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• 제10권3호
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• pp.313-320
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• 2019

In this study, cobalt diselenide ($CoSe_2$) and the composites ($CoSe_2@RGO$) of $CoSe_2$ and reduced graphene oxide (RGO) were synthesized by a facile hydrothermal reaction using cobalt ions and selenide source with or without graphene oxide (GO). The formation of $CoSe_2@RGO$ composites was identified by analysis with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and scanning electron microscopy (SEM). Electrochemical analyses demonstrated that the $CoSe_2@RGO$ composites have excellent catalytic activity for the reduction of $I_3{^-}$, possibly indicating a synergetic effect of $CoSe_2$ and RGO. As a consequence, the $CoSe_2@RGO$ composites were applied as a counter electrode in DSSC for the reduction of redox couple electrolyte, and exhibiting the comparable power conversion efficiency (7.01%) to the rare metal platinum (Pt) based photovoltaic device (6.77%).

• 한국해양바이오학회지
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• 제10권2호
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• pp.34-43
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• 2018

Silicon has become of increasing importance as the basic element of many high-technology products. Its synthesis is very difficult requiring high temperature solid-state reactions (> $1000^{\circ}C$) or lower temperature methods ($100-200^{\circ}C$) involving hydrothermal and solvothermal reactions under extreme pH conditions. In nature, on the other hand, a wide range of living organisms have collectively evolved the means of biosilicification at the astounding rate of gigatons/year. This is impressive because biosilicification in these organisms occurs under mild physiological conditions. Marine sponges possess the ability to sequester soluble silicon sources from their environments and assemble them into intricate 3D architecture. The advent of molecular biology has recently made it possible to glean molecular information about biosilicification from these systems and it turned out that enzyme silicatein is the core of biosilicification. In this review, biosilicification regulated by silicatein and its mechanism are described. Also, production of silicatein through recombinant technology and several applications of recombinant silicatein are described including immobilization of silicatein, formation of Au or Ag nanoparticles on nanowires, nanolithography approaches, core-shell materials, encapsulation, bone replacement materials, and microstructured optical fibers.