• Journal of the Korean institute of surface engineering
• /
• v.51 no.4
• /
• pp.237-242
• /
• 2018

We report on the fabrication and photoelectrochemical (PEC) properties of a ZnO nanorod array structure as an efficient photoelectrode for hydrogen production from sunlight-driven water splitting. Vertically aligned ZnO nanorods were grown on an indium-tin-oxide-coated glass substrate via seed-mediated hydrothermal synthesis method with the use of a ZnO nanoparticle seed layer, which was formed by thermally oxidizing a sputtered Zn metal thin film. The structural and morphological properties of the synthesized ZnO nanorods were examined using X-ray diffraction and scanning electron microscopy, as well as Raman scattering. The PEC properties of the fabricated ZnO nanorod photoelectrode were evaluated by photocurrent conversion efficiency measurements under white light illumination. From the observed PEC current density versus voltage (J-V) behavior, the vertically aligned ZnO nanorod photoelectrode was found to exhibit a negligible dark current and high photocurrent density, e.g., $0.65mA/cm^2$ at 0.8 V vs Ag/AgCl in a 1 mM $Na_2SO_4$ electrolyte. In particular, a significant PEC performance was observed even at an applied bias of 0 V vs Ag/AgCl, which made the device self-powered.

• Bulletin of the Korean Chemical Society
• /
• v.21 no.12
• /
• pp.1239-1244
• /
• 2000

A study of K addition to the catalyst of CoMo/ ${\gamma}-Al_2O_3$ was studied. The catalyst with 10 at% of K to Mo atoms in 3C10M, the catalyst added 3 wt% CoO to 10 wt% $MoO_3/{\gamma}-Al_2O_3$, showed the highest activity for water gas shift reaction. The addition of K retarded the reducibility of cobalt-molybdenum catalysts. It gave, however, good dispersion and large BET surface area to the catalysts which were attributed to the disappearance of polymolybdate clustyer such as $Mo_7O_{24}^{6-}$ and the formation of small Mo$O_4^{2-}$ cluster. It was confirmed by the analyses of pore size distribution, activation energy, Raman spectroscopy, and electron diffraction. The activation energies and the frequency factors of the catalysts 3C10M and 5KC10M (the catalyst added 5 at% K for Mo to the catalyst 3C10M) were 43.1 and 47.8 kJ/mole, and 4,297 and 13,505 $sec^{-1}$, respectively. These values were also well correlated with our suggestion. These phenomena were attributed to the direct interaction between K and CoMo oxides irrelevant to the support.

• Elastomers and Composites
• /
• v.55 no.4
• /
• pp.321-328
• /
• 2020

Zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and sodium hydroxide (NaOH) were dissolved in distilled water and stirred for 30 min. The resulting solution was sonicated by an ultrasonic wave for 45 min. This solution was washed with distilled water and ethanol after centrifugation; next, it was placed in an electric furnace at 200℃ for 1 h under the flow of Ar gas to obtain zinc oxide nanoparticle. A zinc oxide nanoparticle-(C60) fullerene nanowhisker composite was synthesized using the zinc oxide nanoparticle solution, C60-saturated toluene, and isopropyl alcohol via the liquid-liquid interfacial precipitation method. The zinc oxide nanoparticle and zinc oxide nanoparticle-(C60) fullerene nanowhisker composite were characterized using X-ray diffraction, scanning electron microscopy, and Raman spectroscopy, and they were used for the catalytic degradation of methyl orange (MO) under ultraviolet (at 254 and 365 nm) and ultrasonic irradiation. In addition, the catalytic degradation of MO over the zinc oxide nanoparticle and zinc oxide nanoparticle-(C60) fullerene nanowhisker composite was evaluated using ultraviolet-visible spectroscopy.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.540-540
• /
• 2013

In this studying, we investigated the basic properties of N-doped plasma polymer. The N-doped ethylcyclohexane plasma polymer thin films were deposited by radio frequency (13.56 MHz) plasma-enhanced chemical vapor deposition method. Ethylcyclohexenewas used as organic precursor (carbon source) with hydrogen gas as the precursor bubbler gas. Additionally, ammonia gas [NH3] was used as nitrogen dopant. The as-grown polymerized thin films were analyzed using ellipsometry, Fourier-transform infrared [FT-IR] spectroscopy, Raman spectroscopy, FE-SEM, and water contact angle measurement. The ellipsometry results showed the refractive index change of the N-doped ethylcyclohexene plasma polymer film. The FT-IR spectrashowed that the N-doped ethylcyclohexene plasma polymer films were completely fragmented and polymerized from ethylcyclohexane.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08b
• /
• pp.1625-1628
• /
• 2007

Dispersion of arc-discharged single-walled carbon nanotubes (SWNTs) has been accomplished by a water soluble polymer wrapping functionalization at room temperature. The treated SWNTs were redispersed in both aqueous and many organic solvents and the solutions were found to be stable.

• Journal of the Korean Ceramic Society
• /
• v.34 no.2
• /
• pp.171-174
• /
• 1997

It was experimentally identified, for the first time, that oxygen phonons play an important role in the low temperature degradation(tetragonallongrightarrowmonoclinic phase transformation) of yttria stabilized tetragonal zir-conia polycrystals (Y-TZP). The degradation accompanied by immersing the samples in the boiling water were markedly reduced by substituting of 18O for 16O in Y-TZP. This was attributed to the heavier mass of 18O which leads to the smaller probability to find oxygen atoms beyond certain critical displacements.

• Journal of the Korean Chemical Society
• /
• v.53 no.5
• /
• pp.565-569
• /
• 2009

The interaction between polyvinylpyrrolidone(PVP) and silver cation has been studied in water at room temperature and atmospheric pressure. The PVP and PVP/Ag composite was observed by transmission electron microscopy (TEM), UV-VIS absorption spectroscopy, Raman spectroscopy and oxygen/carbon dioxide analyzer. We identified silver cations interacting with nonbonding electrons of the oxygen atom in the carbonyl group of PVP. It was shown that PVP/Ag formed stable composites.

• Journal of the Korean Chemical Society
• /
• v.57 no.3
• /
• pp.352-356
• /
• 2013

In this work, a new cadmium complex $[Cd(L)(CH_3COO)_2].2H_2O$ (1) with the ligand L, N,N'-bis(2-pyridinecarboxalidene)-1,2-cyclohexanediamine was prepared and identified by elemental analysis, FT-IR, Raman, $^1H$ NMR spectroscopy and single-crystal X-ray diffraction. The cadmium atom in the crystal structure of 1 has distorted triangular dodecahedral geometry by coordination of the four nitrogen atoms of L and four oxygen atoms of the two acetate ions. Two water molecules are also incorporated in the crystal network. The $O-H{\cdots}O$ hydrogen bonds present in the crystal structure of 1. In this work, three structural surveys including coordination numbers of the cadmium atom, coordination modes of L and resonance in pyridine-2-ylmethanimine-based compounds are presented.

• Journal of the Korean institute of surface engineering
• /
• v.29 no.5
• /
• pp.487-493
• /
• 1996

Diamond films were grown at lower temperatures (630-813K) on Si, Al (1100P), and Al-Si(8A, 8B, BC) alloy substrates using improved microwave plasma CVD apparatus in a mixed methane and hydrogen plasma. Improved microwave plasma CVD apparatus equipped water cooled substrate holder and the substrates were set up lower position than bottom line of the applicator waveguide. When the methane concentration was high and growth was conducted at lower pressures the diamond films were synthesized. Moreover the deposits on the scratched substrates formed flat surfaces consisting of fine grains. XRD results, the deposits were identified to cubic diamond. An analysis using Raman spectroscopy, further confirmed that diamond films deposited on the Si substrates were high quality. The deposits on the Al substrates, in contrast, contained amorphous carbon. While the quality of the deposits on the Al-Si substrates were differed with the substrate alloys.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.159-159
• /
• 2013

In this studying, we investigated the basic properties of N-doped plasma polymer. The N-doped plasma polymer thin films were deposited by radio frequency (13.56 MHz) plasma-enhanced chemical vapor deposition method. Various carbon-source were used as organic precursor with hydrogen gas as the precursor bubbler gas. Additionally, ammonia gas [NH3] was used as nitrogen dopant. The as-grown polymerized thin films were analyzed using cyclic voltammetry, ellipsometry, Fourier-transform infrared [FT-IR] spectroscopy, Raman spectroscopy, FE-SEM, and water contact angle measurement. Electronic property of N-doped plasma thin film is changed as flow rate of the NH3 gas.