• Environmental Engineering Research
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• v.14 no.2
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• pp.134-139
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• 2009

In this study, oxidation of As (III) as well as removal of total arsenic by adsorbents coated with single oxides or multi-oxides (Fe (III), Mn (IV), Al (III)) was investigated. In addition, multi-functional properties of adsorbents coated with multi-oxides were evaluated. Finally, application of activated carbon impregnated with Fe or Mn-oxides on the treatment of As (III) or As (V) was studied. As (V) adsorption results with adsorbents containing Fe and Al shows that adsorbents containing Fe show a greater removal of As (V) at pH 4 than at pH 7. In contrast adsorbents containing Al shows a favorable removal of As (V) at pH 7 than at pH 4. In case of iron sand, it has a negligible adsorption capacity for As (V) although it contains 217.9 g-Fe/kg-adsorbent, Oxidation result shows that manganese coated sand (MCS) has the greatest As (III) oxidation capacity among all metal oxides at pH 4. Oxidation efficiency of As (III) by IMCS (iron and manganese coated sand) was less than that by MCS. However the total removed amount of arsenic by IMCS was greater than that by MCS.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3183-3189
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• 2010

In order to increase the specific capacitance and energy density of supercapacitors, non-aqueous supercapacitors were prepared using lithium transition-metal oxides and activated carbons as active materials. The electrochemical properties were analyzed in terms of the content of lithium transition-metal oxides. The results of cyclic voltammetry and AC-impedance analyses showed that the pseudocapacitance may stem from the synergistic contributions of capacitive and faradic effects; the former is due to the electric double layer which is prepared in the interface of activated carbon and organic electrolyte, and the latter is due to the intercalation of lithium ($Li^+$) ions. The specific capacitance and energy density of a supercapacitor improved as the lithium transition-metal oxides content increased, showing 60% increase compared to those of supercapacitor using a pure activated carbon positive electrode.

• Korean Journal of Materials Research
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• v.19 no.10
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• pp.533-537
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• 2009

This paper presents a new method for the improvement of color temperature without the change of the driving scheme using transparent dielectric layers with various metal oxides (CeO$_2$, Co$_3$O$_4$, CuO, Fe$_2$O$_3$, MnO$_2$, NiO) in plasma display panels (PDP). In this study, we fabricated ZnO-B$_2$O$_3$-SiO$_2$-Al$_2$O$_3$ glasse with various metal oxides and examined the optical properties of these glasses. As the metal oxides were added to the glasses, the visible transmittances of the dielectric layers decreased and the transmittances in special wavelength regions were reduced at different rates. The change of the transmittance in each wavelength range induced the variation of the visible emission spectra and the change of the color temperature in the PDP. The addition of Co$_3$O$_4$ and CuO slightly decreased the intensity of the blue light, but the intensities of the green and the red light were significantly decreased. Therefore, the color temperature can be improved from 6087K to 7378K and 7057K, respectively.

• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.2073-2080
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• 2013

In this study the effects of adding alkaline-earth (IIA) metal oxides to NiZr-loaded Zeolite Y catalysts were investigated on hydrogen rich production by ethanol steam reforming (ESR). Four kinds of alkaline-earth metal (Mg, Ca, Sr, or Ba) oxides of 3.0% by weight were loaded between the $Ni_6Zr_4O_{14}$ main catalytic species and the microporous Zeolite Y support. The characterizations of these catalysts were examined by XRD, TEM, $H_2$-TPR, $NH_3$-TPD, and XPS. Catalytic performances during ESR were found to depend on the basicity of the added alkaline-earth metal oxides and $H_2$ production and ethanol conversion were maximized to 82% and 98% respectively in 27($Ni_6Zr_4O_{14}$)3MgO/70Zeolite Y catalyst at $600^{\circ}C$. Many carbon deposits and carbon nano fibers were seen on the surface of $30Ni_6Zr_4O_{14}$/70Zeolite Y catalyst but lesser amounts were observed on alkaline-earth metal oxide-loaded 27($Ni_6Zr_4O_{14}$)3MO/70Zeolite Y catalysts in TEM photos after ESR. This study demonstrates that hydrogen yields from ESR are closely related to the acidities of catalysts and that alkaline-earth metal oxides reduce the acidities of 27($Ni_6Zr_4O_{14}$)3MO/70Zeolite Y catalysts and promote hydrogen evolution by preventing progression to hydrocarbons.

• The Korean Journal of Ceramics
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• v.6 no.4
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• pp.370-379
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• 2000

Simple ways to build up mixed-metal molecules which can act as potential single-source precursors to multimetallic oxides are reviewed. Emphasis is given to Lewis acid-base reactions between metal alkoxides M(OR)/sub n/, and between metal alkoxides and more accessible oxide precursors, carboxylates M(O₂CR)/sub n/ and β-diketonates M(β-dik)/sub n/. Characterization of the precursors is achieved in the solid state (single crystal X-ray diffraction, FT-IR) and by multinuclear NMR in solution. The reactions proceed toward the formation of aggregates in which the different metals display their usual coordinations numbers, often six for transition metals, as shown. Strategies for fixing the stoichiometry between the metals are developed. The reactivity of the MM species (dissociation, effects of chemical modifiers, of other metallic species, hydrolytic or non-hydrolytic condensation, etc.) will be indicated. Transformations into oxides are illustrated on precursors for titanates or niobates.

• Journal of the Korean Ceramic Society
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• v.47 no.1
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• pp.8-18
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• 2010

When metal oxides are exposed to chemical potential gradients, ions are driven to diffusive mass transport. During this transport process, the divergence of ionic fluxes offers the formation/annihilation of oxides. Therefore, the divergence of ionic flux may play an important role in the void formation in oxides. Kinetic equations were derived for describing chemical potential distribution, ionic fluxes and their divergence in oxides. The divergence was found to be the measure of void formation. Defect chemistry in scales is directly related to the sign of divergence and gives an indication of the void formation behavior. The quantitative estimation on the void formation was successfully applied to a growing magnetite scale in high temperature oxidation of iron at 823 K.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.387.1-387.1
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• 2016

Transparent materials are necessary for most photoelectric devices, which allow the light generation from electric energy or vice versa. Metal oxides are usual materials for transparent conductors to have high optical transmittance with good electrical properties. Functional designs may apply in various applications, including solar cells, photodetectors, and transparent heaters. Nanoscale structures are effective to drive the incident light into light-absorbing semiconductor layer to improve solar cell performances. Recently, the new metal oxide materials have inaugurated functional device applications. Nickel oxide (NiO) is the strong p-type metal oxide and has been applied for all transparent metal oxide photodetector by combining with n-type ZnO. The abrupt p-NiO/n-ZnO heterojunction device has a high transmittance of 90% for visible light but absorbs almost entire UV wavelength light to show the record fastest photoresponse time of 24 ms. For other applications, NiO has been applied for solar cells and transparent heaters to induce the enhanced performances due to its optical and electrical benefits. We discuss the high possibility of metal oxides for current and future transparent electronic applications.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.45-48
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• 2007

Thermochemical 2-step methane reforming, involving the reduction of metal oxide with methane to produce syn-gas and the oxidation of the reduced metal oxide with water to produce pure hydrogen, was investigated on ferrite-based metal oxide mediums and $WO_{3}/ZrO_{2}$. Thermochemical 2-step methane reforming were accomplished at 900 $^{\circ}C$(syn-gas production step) and 800 $^{\circ}C$(water-splitting step). In syn-gas production step, it appeared carbon deposition on metal oxides with increasing react ion time. Various mediums showed the different starting point of carbon deposition each other. To minimize the carbon deposition, the reaction time was controlled before the starting point of carbon deposition. As a result, $CO_{x}$ were not evolved in water-splitting step, Among the various metal oxides, $Mn-ferrite/ZrO_{2}$ showed high reactivity, proper $H_{2}/CO$ ratio, high selectivity of undesired $CO_{2}$ and high evolution of $H_{2}$.

• Korean Journal of Materials Research
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• v.9 no.5
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• pp.441-445
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• 1999

Alkaline earth metal oxides were added to the conventional MgO films as a protective layer for dielectric materials to have lower firing voltage(Vf) of the plasma display panel(PDP). Panels with various protective layers of MgO-alkaline earth metal oxides were prepared on glass by using e-beam evaporation and its effect on firing voltage characteristics were investigated. (Ba-Mg)O films had poor voltage characteristics because of higher activation energy of BaO. But, (Sr-Mg)O, (Ca-Mg)O and (Ca-Sr-Mg) O had better voltage characteristics than the conventional MgO. A mixture film of (Mg-Ca-Sr)O show the lowest firing voltage which is less than that of MgO by 20V. The chemical composition to have lowest firing voltage is MgO:SrO:CaO ratio of 6:2:2. The mixture of MgO-Alkaline earth metal oxides films showed good transmittance properties within the visual range.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.3
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• pp.68-75
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• 2001

In this paper, a number of supported metal oxides and perovskite type catalysts were investigated for the NOx reduction from the diesel engine exhaust gas. All catalysts were made into pellets type with diameter of 3-4 mm alumina(Al$_2$O$_3$) as a supporter. These samples were tested by real diesel exhaust gas which contains CO, hydrocarbons and soot in the temperature range of 150~55$0^{\circ}C$ with the $3300h^{-1}$ space velocity (SV). Among the results, several promising catalysts showed NOx conversion above 50% in the temperature range of 150-35$0^{\circ}C$. From these results supported metal oxides catalysts and perovskite type could be recommended for the practical application to the automobile exhaust treatments.