• Applied Chemistry for Engineering
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• v.27 no.4
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• pp.421-426
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• 2016

In this report, polyoxometalte (POM)-doped polypyrrole (Ppy) was deposited on surface of three-dimensional carbon cloth (CC) using an electrodeposition method and its pseudocapacitive behavior was investigated using cyclic voltammetry and galvanostatic charge-discharge. The POM-Ppy coating was thin and conformal which can be controlled by electrodeposition time. As-prepared POM-Ppy/CC was characterized using scanning electron microscope and energy-dispersive X-ray spectroscopy. The unique 3D nanocomposite structure of POM-Ppy/CC was capable of delivering excellent charge storage performances: a high areal capacitance ($561mF/cm^2$), a high rate capability (85%), and a good cycling performance (97% retention).

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.1
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• pp.26-30
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• 2004

Orientation control of a polyoxometalate (POM) nanoparticle in its two-dimensional arrangement was attempted by Langmuir-Blodgett (LB) technique. For their uniorientation, two carboxyl groups were introduced on one side of the POM particle, and hydrophobic long chains were attached by esterification with the carboxyl groups (C18-POM). The C18-POM layer spread on water surface showed stability against surface pressure up to 60 mN/m. The pattern of the C18-POM isotherm was quite different from stearyl alcohol (C18-OH), while the POM itself did not show any development of surface pressure on water surface. The AFM images of C18-POM LB films showed some microcrystalline structures that were noticed as dot structures by Brewster angle microscopy. The microimages for C18-POM did not completely spread out as a monolayer on the water surface. The XPS spectra indicated the presence of POM structures and stearyl ester bonds formed from about 65% of the total carboxyls. The XRD spectra showed that the unioriented POMs were not positioned with the same lattice distance but rather in a wavy surface state.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.609-611
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• 2004

Sodium salt of photoluminescent Eu-containing polyoxometalate (Eu-POM) was newly synthesized and its chemical structure and physical properties characterized. The Eu-POM was unstable outside the pH range 5.5-8.5, and a pH just over 7 gave the best yield. We have investigated the photoluminescent properties of Eu-POM with changing the reactants ratio of heteropolytungstate and $EuCl_3{\cdot}6H_2O}$. The Eu-POM was characterized by UV/Vis, FT-IR, $^1H$-NMR, PL and XPS. Eu-POM emits orange light of 590nm when excited with the light of 280nm. Furthermore, we made dodecyltrimethylammonium (DDTA) salt of Eu-POM (Eu-POM/DDTA) by exchange of the counter cation. The Eu-POM/DDTA is soluble in common organic solvents, while Eu-POM is only soluble in water. And it emits reddish orange light of 625nm when excited with light of 250nm.

• Bulletin of the Korean Chemical Society
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• v.18 no.4
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• pp.369-373
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• 1997

When 1H NMR spectra of pyridine, 4-amino-, 4-methyl-, and 4-cyanopyridine coordinated to the paramagnetic polyoxometalate, [SiW11CoⅡO39]6- in D2O are compared, both α- and β-proton peaks are shifted upfield as the basicity of the ligand decreases. The isotropic shifts are separated into contact and pseudocontact contributions by assuming that the contact shifts are proportional to the isotropic shifts of the same ligands coordinated to [SiW11NiⅡO39]6-. This separation reveals that the shift variations with the axial ligand basicity are dominated by changes in the magnetic anisotropy (pseudocontact shift) of [SiW11CoⅡ(ptl)O39]6- (ptl=pyridine-type ligand). The magnitude of the magnetic anisotropy in a series of pyridine-type ligands increases linearly as the pKa of their conjugate acids decreases.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2482-2484
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• 2011

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.1931-1932
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• 2014

• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.599-600
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• 2004

• Bulletin of the Korean Chemical Society
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• v.24 no.7
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• pp.1005-1008
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• 2003

• Applied Chemistry for Engineering
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• v.29 no.4
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• pp.363-368
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• 2018

Polyoxometalates (POMs) have outstanding properties and a great deal of potential for electrochemical applications. As POMs are highly soluble, the implementation of POMs in various functional materials is required to fully use their potential in electrochemical devices. Here, we will review the recently developed immobilization methods to incorporate POMs into conductive nanomaterials, such as nanocarbons and conducting polymers. Various immobilization strategies involve POMs entrapped in conducting polymer matrix and integration of POMs into nanocarbons using a Langmuir-Blodgett technique, a layer-by-layer self-assembly, and an electrochemical in-situ polymerization. In addition, we will review a variety of electrochemical applications including electrocatalysts for water oxidation, lithium-ion batteries, supercapacitors, and electrochemical biosensors.

• Bulletin of the Korean Chemical Society
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• v.31 no.1
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• pp.104-111
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• 2010

The heterogeneous electron transfer at $SiMo_{12}O_{40}^{4-}$ monolayers on GC, HOPG, and Au electrode surfaces are investigated using cyclic voltammetric and electrochemical impedance spectroscopic (EIS) methods. The electron transfer of negatively charged $Fe(CN)_6^{3-}$ species is retarded at $SiMo_{12}O_{40}^{4-}$-modified electrode surfaces, while that of positively charged $Ru(NH_3)_6^{3+}$species is accelerated at the modified surfaces. This is due to the electrostatic interactions between $SiMo_{12}O_{40}^{4-}$ layers on surfaces and charged redox species. The electron transfer kinetics of a neutral redox species, 1,1‘-ferrocenedimethanol (FDM), is not affected by the modification of electrode surfaces with $SiMo_{12}O_{40}^{4-}$, indicating the $SiMo_{12}O_{40}^{4-}$ monolayers do not impart barriers to electron transfer of neutral redox species. This is different from the case of thiolate SAMs which always add barriers to electron transfer. The effect of $SiMo_{12}O_{40}^{4-}$ layers on the electron transfer of charged redox species is dependent on the kind of electrodes, where HOPG surfaces exhibit marked effects. Possible mechanisms responsible for different electron transfer behaviors at $SiMo_{12}O_{40}^{4-}$ layers are proposed.