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Author: search.filters.author.Otgonbayar, Zambaga

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    Magnetic and ultrasonic integrated photocatalytic hydrogen evolution effects with Nanosize CoOCu2OZnO and TiO2 decorated on reduced graphene oxide
    (2023-12-01)
    Areerob, Yonrapach
    ;
    Meng, Zeda
    ;
    Ullah, Kefayat
    ;
    Wijaya, Karna
    ;
    Otgonbayar, Zambaga
    In this study, metal oxide composite (CoOCu<inf>2</inf>OZnO) and TiO<inf>2</inf> on graphene oxide composite (CCZ−G−T) were synthesized to improve visible light-driven H<inf>2</inf> evolution through the addition of a cation scavenger, ultrasonic effect, and magnetic field effect. The synthesized nanocomposites were characterized through structural, surface, and electrochemical analyses with band structure. The photocatalyst showed hydrogen production of 792 μmol·g<sup>−1</sup> for 4 hours. Moreover, this CCZ−G−T photocatalyst exhibits relatively high photocatalytic activity at (530−810) μmol·g<sup>−1</sup> when using a scavenger, 1,190 μmol·g<sup>−1</sup> when using a magnetic field of 0.14 T, and 1,230 μmol·g<sup>−1</sup> when using ultrasonic waves. The CCZ−G−T composite exhibited 630 μmol·g<sup>−1</sup> under a magnetic field condition of 0.14 T for 1 hour, which was significantly higher than the hydrogen production rate of 510 μmol·g<sup>−1</sup> under ultrasonic conditions. The current study provides new insights into the magnetic field effect on the hydrogen evolution reaction (HER) of graphene-based photocatalysts.
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    Lithium Amount Effect of Li-Inserted Ultra-Surface Area-Activated Carbon and Improvement of the Electrochemical Performance with Magnetic Field for Li-Ion Capacitors
    (2022-12-27)
    Otgonbayar, Zambaga
    ;
    Areerob, Yonrapach
    ;
    Yang, Sunhye
    ;
    Kim, Ick Jun
    ;
    Oh, Won Chun
    It is possible that controlling the lithium-ion amount may relate to the high energy and the specific capacitance of active materials into a single device. As the cathode for Li-ion capacitors (LICs) using nonaqueous electrolytes, we investigated surface functionalization of ultra-surface area-activated carbon (UAC) powder. An increase in capacitance was observed, from 1.25 × 104 to 8.10 × 104 F/g with controlling of lithium amount, as well as an increase in the area explicit capacitance per BET surface region from 657.57 to 1605.25 m2/g, which indicates that redox responses and their remarkable potential might enhance the capacitance for LICs. The pseudocapacitive redox reaction at C=O destinations is mostly attributed to capacitance enhancement. As with the improvement in capacitance, it was discovered that the arrangement of the electrolytes depends on the wetting behavior and particle size that can be adjusted. This study suggests the way for a low-cost and widely used UAC powder with controlling of lithium amount and a magnetic field for LICs. The 6LUAC samples treated with a magnetic field showed excellent specific capacity and energy density compared to samples not treated with a magnetic field under the same test conditions. Finally, we expect that this method may contribute to improvement of the electrochemical performance of materials.
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    Comparative catalytic approach of Ag doped ZnO with various nanocarbon materials toward CO2reduction with magnetic field and carbon form dependence
    (2022-12-01)
    Otgonbayar, Zambaga
    ;
    Areerob, Yonrapach
    ;
    Oh, Won Chun
    Graphene oxide (GO) is a compromising catalyst material with a two-dimensional layer of carbon atoms having sp2 hybridization bonded in a hexagonal lattice structure. The gCN is a member of 2D-structured metal-free carbon materials. In this study, GO, gCN, fluorine, and nitrogen treated GO and ZnO-Ag (Ag doped ZnO) loaded carbon nanocomposites were studied. Fluorine and nitrogen treated GO is an up-rising carbon member. It has high stability. Its layer structure possess unique properties due to its C-F (covalent and semi -ionic) and C-N bonds. The computer simulations of all molecules were conducted using the Hartree-Fock function with a 6-311 G∗ mode on Spartan'14 software. A number of properties like molecule structure, electrostatic potential, local ionization potential, density, HOMO, and LUMO level of the molecules were obtained from computer simulations. Electrochemical CO<inf>2</inf> reduction to CH3OH on catalysts was investigated in different electrolysis conditions, such as different electrolytes with UV-light and 0.07 T magnetic core treatment. Results showed that the introduction of ZnO-Ag on carbon nanocomposites improved properties of carbon nanocomposites, leading to a high conversion of CO<inf>2</inf> to CH3OH. Methanol production rate was improved by five-times after UV-light (λ = 254 nm) and 0.07 T magnetic core treatment. Faradaic efficiencies of carbon nanocomposites for methanol production through electrochemical reduction of CO<inf>2</inf> in bicarbonate buffer and electrolytes were found to be 67.48% and 58.93% (compared to Ag/AgCl) at - 2.7 V, respectively. Charge carrier properties and morphology profile of these nanocomposites were also analyzed.