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Author: search.filters.author.Winadda, WongwiriyapanSubject: search.filters.subject.Manganese oxide

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    Carbon nanotube/manganese oxide thin film composites-based counter electrode for dye-sensitized solar cell
    (2016-01-01)
    Nathakreat, Ketama
    ;
    Wirat, Jarernboon
    ;
    Winadda, Wongwiriyapan
    Manganese oxide thin film sandwiched between carbon nanotubes thin films-coated on fluorine-doped tin oxide (FTO/CNT/MnO<inf>x</inf>/CNT) was used as a counter electrode of dye-sensitized solar cell (DSSC) for performance improvement. The multi-layer electrodes were fabricated by sequential process comprising doctor-blade coating of CNT layer and the following electroplating coating of MnO<inf>x</inf> layer and subsequent doctor-blade coating of CNT layer once again. The multi-layered counter electrode of CNT/MnO<inf>x</inf>/CNT exhibited the improved conversion efficiency and a fill factor of 2.01±0.01% and a fill factor of 0.55±0.01, respectively, due to an increase in capacitance of the electrode. Electrochemical impedance spectra (EIS) show that the capacitance of multi-layered CNT/MnO<inf>x</inf>/CNT electrode increased from 22±3 μF to 41±2 μF comparing to that of a monolayer of CNT. Furthermore, EIS of FTO/CNT/MnO<inf>x</inf>/CNT-based DSSC shows the smallest radius of the semicircle with a charge transfer resistance of 42 ω, implying a quick redox reaction between counter electrode and electrolyte. The improved fill factor is likely due to the role of MnO<inf>x</inf> that increases the capacitance of electrode and reduces electron transfer rate from counter electron to electrolyte.
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    Electrodeposition of manganese oxide nanosheets as supercapacitor electrode materials
    (2016-01-01)
    Thanthamrong, Wanchaem
    ;
    Songsak, Rattanamai
    ;
    Paweena, Dulyaseree
    ;
    Wirat, Jarernboon
    ;
    Winadda, Wongwiriyapan
    Manganese oxide (MnO<inf>x</inf>) thin films were prepared on stainless steel (SS) 304 by galvanostatic (GS) mode of electrodeposition technique using different precursors; 0.1 M potassium permanganate (KMnO<inf>4</inf>) and 0.1 M manganese sulfate (MnSO<inf>4</inf>) solutions. The electrodeposition condition was set at a constant current of 1 mA/cm2. Different precursors provide MnO<inf>x</inf> thin films with different morphologies. Using KMnO<inf>4</inf> as a precursor, the MnO<inf>x</inf> thin film was deposited (MnO<inf>x</inf>-K), while using MnSO<inf>4</inf> as a precursor, the MnO<inf>x</inf> nanosheets with a thickness of approximately 40 nm were formed (MnO<inf>x</inf>-S). XPS results evidence the formation of manganese oxide with different oxidation states composition by different precursors. Electrochemical measurements were carried out in a three-electrode setup using Pt and Ag/AgCl electrodes as counting and reference electrodes, respectively and 1M Na<inf>2</inf>SO<inf>4</inf> aqueous solution as electrolyte. MnO<inf>x</inf>-K at a deposition time of 10 min shows the highest specific capacitance of 233.55±19.01 F/g. The specific capacitance improvement of MnO<inf>x</inf>-K may be attributed to MnO<inf>x</inf> nanosheet structure which increases surface area of electrode.