• Title/Summary/Keyword: (Photo)electrochemical properties

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Facile Preparation of Ag2S-CNT Nanocomposites with Enhanced Photo-catalytic Activity

  • Meng, Ze-Da;Sarkar, Sourav;Zhu, Lei;Ullah, Kefayat;Ye, Shu;Oh, Won-Chun
    • Journal of the Korean Ceramic Society
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    • v.51 no.1
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    • pp.1-6
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    • 2014
  • Here we report improved photo-catalytic effect of $Ag_2S$ under visible light using carbon nano-tubes (CNT) modified with $Ag_2S$ nanoparticles. The optical properties, structural properties and compositional analysis, as well as the photo-electrochemical properties of the prepared composites were investigated. It was found that the photocurrent density, and the photo-catalytic effect, was increased by modification of CNT in this way. Compared with the separate effects of $Ag_2S$ and CNT nanoparticles, the photocatalytic effect of CNT-modified-with-$Ag_2S$ composites, increased significantly due to a synergistic effect between the CNT and the $Ag_2S$ nanoparticles.

Studies on the Photo-electrochemical Properties of Ti$O_{2-x}$ Thin Films (Ti$O_{2-x}$ 박막의 광-전기화학적 성질에 관한 연구)

  • Q Won Choi;Chu Hyun Choe;Ki Hyung Chjo;Yong Kook Choi
    • Journal of the Korean Chemical Society
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    • v.29 no.6
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    • pp.582-591
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    • 1985
  • The thin films of Ti$O_{2-x}$, were prepared by vapor oxidation and Ti$O_2$ single crystal was reduced by heating in argon atmosphere. The photo-electrochemical properties of these samples were studied. When the photocurrent was scanned in 1M NaOH electrolyte solution, several peaks were observed in the vicinity of 320nm in the UV-region and in the vicinity of 520nm, 620nm, and 740nm in the visible-region. Contrary to the previous suppositions, those peaks were produced by the second-order lines from the grating monochromator.

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Fabrication and (Photo)Electrochemical Properties of Fe2O3/Na2Ti6O13/FTO Films for Water Splitting Process (물분해용 Fe2O3/Na2Ti6O13/FTO 박막 제조 및 특성평가)

  • Yun, Kang-Seop;Ku, Hye-Kyung;Kang, Woo-Seung;Kim, Sun-Jae
    • Corrosion Science and Technology
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    • v.11 no.2
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    • pp.65-69
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    • 2012
  • One dimensional(1D) $Na_2Ti_6O_{13}$ nanorods with 70 nm in diameter was synthesized by a molten salt method. Using the synthesized nanorods, about 750 nm thick $Na_2Ti_6O_{13}$ film was coated on Fluorine-doped tin oxide(FTO) glasss substrate by the Layer-by-layer self-assembly(LBL-SA) method in which a repetitive self-assembling of ions containing an opposite electric charge in an aqueous solution was utilized. Using the Kubelka-Munk function, the band gap energy of the 1D-$Na_2Ti_6O_{13}$ nanorods was nalyzed to be 3.5 eV. On the other hand, the band gap energy of the $Na_2Ti_6O_{13}$ film coated on FTO was found to be a reduced value of 2.9 eV, resulting from the nano-scale and high porosity of the film processed by LBL-SA method, which was favorable for the photo absorption capability. A significant improvement of photocurrent and onset voltage was observed with the $Na_2Ti_6O_{13}$ film incorporated into the conventional $Fe_2O_3$ photoelectrode: the photocurrent increased from 0.25 to 0.82 mA/$cm^2$, the onset voltage decreased from 0.95 to 0.78 V.

Studies on the Photo-Electrochemical Properties of Ti$O_2$-x Thin Films Prepared by Air Oxidation and Water Vapor Oxidation (공기 산화와 수증기 산화에 의해 제조된 Ti$O_2$-x박막의 광전기화학적 성질에 관한 연구)

  • Choi Yong-Kook;Jo, Gi Hyeong;Choi Q-Won;Oh Jeong-Geun;Seong Jeong-Sub
    • Journal of the Korean Chemical Society
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    • v.37 no.6
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    • pp.549-554
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    • 1993
  • The titanium oxide thin film was prepared by air oxidation and water vapor oxidation. The photo-electrochemical properties of the electrode was studied in 1M NaOH solution. Titanium dioxide electrodes prepared at higher temperatures were found to have slightly more negative flat band potentials and slightly higher donor densities than their low temperature counterparts. The value of flat band potential ($V_{fb}$) was obtained to be -0.95 ∼ -1.1 V by the measurement of photocurrent and Motte-Schottky plots. The photocurrent of visible region was measured in terms of single crystal filter which entirely blocks the UV radiation. The photo-response of electrodes appeared good with the measument by direct current, when the slit of great resolution was used.

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Preparation of UV Curable Gel Polymer Electrolytes and Their Electrochemical Properties

  • Oh, Boo-Keun;Jung, Won-Il;Kim, Dong-Won;Rhee, Hee-Woo
    • Bulletin of the Korean Chemical Society
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    • v.23 no.5
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    • pp.683-687
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    • 2002
  • We have investigated the effect of the number of ethylene oxide (EO) units inside poly(ethylene glycol)dimethacrylate (PEGDMA) on the ionic conductivity of its gelled polymer electrolyte, whose content ranges from 50 to 80 wt%. PEGDMA gelled polym er electrolytes, a crosslinked structure, were prepared using simple photo-induced radical polymerization by ultraviolet light. The effect of the number of EO on the ionic conductivity was clearly shown in samples of lower liquid electrolyte content. We have concluded that the ionic conductivity increased in proportion to both the number of EO units and the plasticizer content. We have also studied the electrochemical properties of 13PEGDMA (number of EO units is 13) gelled polymer electrolyte.

Sputtered Al-Doped ZnO Layers for Cu2ZnSnS4 Thin Film Solar Cells

  • Lee, Kee Doo;Oh, Lee Seul;Seo, Se-Won;Kim, Dong Hwan;Kim, Jin Young
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.688-688
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    • 2013
  • Al-doped ZnO (AZO) thin films have attracted a lot of attention as a cheap transparent conducting oxide (TCO) material that can replace the expensive Sn-doped In2O3. In particular, AZO thin films are widely used as a window layer of chalcogenide-based thin film solar cells such as Cu(In,Ga)Se2 and Cu2ZnSnS4 (CZTS). Mostly important requirements for the window layer material of the thin film solar cells are the high transparency and the low sheet resistance, because they influence the light absorption by the activelayer and the electron collection from the active layer, respectively. In this study, we prepared the AZO thin films by RF magnetron sputtering using a ZnO/Al2O3 (98:2wt%) ceramic target, and the effect of the sputtering condition such as the working pressure, RF power, and the working distance on the optical, electrical, and crystallographic properties of the AZO thin films was investigated. The AZO thin films with optimized properties were used as a window layer of CZTS thin film solar cells. The CZTS active layers were prepared by the electrochemical deposition and the subsequent sulfurization process, which is also one of the cost-effective synthetic approaches. In addition, the solar cell properties of the CZTS thin film solar cells, such as the photocurrent density-voltage (J-V) characteristics and the external quantum efficiency (EQE) were investigated.

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Photo-Electrochemical Properties of $TiO_2$ Electrodes Prepared by Anodic Oxidation (양극산화에 의해 제조된 $TiO_2$ 전극의 광전기화학적 성질)

  • Yong Kook Choi;Soon Ki Lee;Q Won Choi;Jeong Sub Seong;Ki Hyung Chjo
    • Journal of the Korean Chemical Society
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    • v.37 no.12
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    • pp.1010-1018
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    • 1993
  • The titanium oxide thin films were prepared by anodic oxidation. The Photo-electrochemical properties of the electrodes were studied in 1 M NaOH solution. The flat band potentials of $TiO_2$ electrodes prepared by anodic oxidation showed around -0.8V and the values were shifted 0.2V to the positive potential direction that of single crystal $TiO_2$. Reduction potential of oxygen by cyclic voltammetry showed around -0.95V vs. SCE and these reactions were processed totally irreversible. The photocurrent of electrodes were showed shorter wavelength than that of single crystal $TiO_2$ and its current density decreased.

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Synthesis and Application of New Ru(II) Complexes for Dye-Sensitized Nanocrystalline TiO2 Solar Cells

  • Seok, Won-K.;Gupta, A.K.;Roh, Seung-Jae;Lee, Won-Joo;Han, Sung-Hwan
    • Bulletin of the Korean Chemical Society
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    • v.28 no.8
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    • pp.1311-1316
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    • 2007
  • To develop photo-sensitizers for dye-sensitized solar cells (DSCs) used in harvesting sunlight and transferring solar energy into electricity, we synthesize novel Ru(II) polypyridyl dyes and describe their characterization. We also investigate the photo-electrochemical properties of DSCs using these sensitizers. New dyes contain chromophore unit of dafo (4,5-diazafluoren-9-one) or phen-dione (1,10-phenanthroline-5,6-dione) instead of the nonchromophoric donor unit of thiocyanato ligand in cis-[RuII(dcbpy)2(NCS)2] (dcbpy = 4,4'-dicarboxy- 2,2'-bipyridine) coded as N3 dye. For example, the photovoltaic data of DSCs using [RuII(dcbpy)2(dafo)](CN)2 as a sensitizer show 6.85 mA/cm2, 0.70 V, 0.58 and 2.82% in short-circuit current (Jsc ), open-circuit voltage (Voc), fill factor (FF) and power conversion efficiency (Eff), which can be compared with those of 7.90 mA/ cm2, 0.70 V, 0.53 and 3.03% for N3 dye. With the same chelating ligand directly bonded to the Ru metal in the complex, the CN ligand increases the Jsc value by double, compared to the SCN ligand. The extra binding ability in these new dyes makes them more resistant against ligand loss and photo-induced isomerization within octahedral geometry.

Electrochemical Properties and Fabrication of Conjugated System Conducting Oligomer Self-assembled Monolayer (공액구조 전도성 올리고머 자기조립단분자막의 제작 및 전기화학적 특성)

  • Min, Hyun Sik;Lee, Tae Yeon;Oh, Se Young
    • Applied Chemistry for Engineering
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    • v.22 no.5
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    • pp.545-550
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    • 2011
  • We have synthesized a high electrically conductive 4-(2-(4-(acetylthio)phenyl)ethynyl)benzoic acid (APBA) with a conjugated aromatic structure as a bio fix linker, and then fabricated APBA self-assembled monolayer (SAM) with a self-assembly technique. The structure of the prepared APBA SAM was studied and electrochemical properties of APBA SAM immobilized with a ferrocene molecule were investigated. Also, we have examined the molecular orientation and oxidation-reduction redox characteristics of the mixed SAM consisting of APBA and butanethiol (BT) with a X-ray photo electron spectroscopy (XPS) and cyclicvoltammetry, respectively. Electrochemical activity of the mixed SAM was increased with increasing the mixed time. Especially, the maximum redox current was obtained at a mixed time of 36 hrs.