Yazar "Demir, Elif" seçeneğine göre listele

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    Ceria supported ruthenium(0) nanoparticles: Highly efficient catalysts in oxygen evolution reaction
    (Academic Press Inc Elsevier Science, 2019) Demir, Elif; Akbayrak, Serdar; Onal, Ahmet M.; Ozkar, Saim
    Ruthenium(0) nanoparticles were successfully prepared on the surface of ceria (Ru-0/CeO2) and used as catalysts on glassy carbon electrode (GCE) in oxygen evolution reaction (OER) from water electrolysis at room temperature. Ru-0/CeO2 on GCE exhibits high catalytic activity for OER in alkaline solution. It provides a low onset potential of 1.57 V vs. RHE and low overpotential of 420 mV vs. RHE to reach a current density of 10 mA cm(-2). Ru-0/CeO2 on GCE shows no change in the onset potential value even after 6.1 h electrochemical measurement in OER. (C) 2018 Elsevier Inc. All rights reserved.
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    Nanoceria-Supported Ruthenium(0) Nanoparticles: Highly Active and Stable Catalysts for Hydrogen Evolution from Water
    (Amer Chemical Soc, 2018) Demir, Elif; Akbayrak, Serdar; Onal, Ahmet M.; Ozkar, Saim
    Ruthenium(0) nanoparticles supported on nanoceria (Ru-0/CeO2) were prepared by reduction of Ru3+ ions on the surface of ceria using aqueous solution of NaBH4. The Ru-0/CeO2 samples were characterized by advanced analytical tools and employed as electrocatalysts on the glassy carbon electrode (GCE) in hydrogen evolution from water. The GCE, modified by Ru-0/CeO2 (1.86 wt % Ru), provides an incredible electrocatalytic activity with a high exchange current density of 0.67 mA.cm(-2), low overpotential of 47 mV at j = 10 mA.cm(-2), and small Tafel slope of 41 mV.dec(-1). Moreover, this modified GCE provides an unprecedented long-term stability without changing the onset potential (33 mV) even after 10 000 scans in acidic water splitting at room temperature. The hydrogen gas, evolved during the water splitting using the Ru-0/CeO2 (1.86 wt % Ru) electrocatalyst, was also collected. The amount of the evolved H-2 gas matches well with the calculated value, which indicates the achievement of nearly 100% Faradaic efficiency.
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    Titania, zirconia and hafnia supported ruthenium(0) nanoparticles: Highly active hydrogen evolution catalysts
    (Academic Press Inc Elsevier Science, 2018) Demir, Elif; Akbayrak, Serdar; Onal, Ahmet M.; Ozkar, Saim
    Designing a cost-effective catalyst with high activity and stability for hydrogen evolution reaction (2H(+) + 2e(-) -> H-2) is a big challenge due to increasing demand for energy. Herein, we report the electrocatalytic activity of glassy carbon electrodes with group 4 metal oxides (TiO2, ZrO2, HfO2) supported ruthenium(0) nanoparticles in hydrogen evolution reaction. Electrochemical activity of modified electrodes is investigated by recording linear sweep voltammograms in 0.5 M H2SO4 solution. The results of electrochemical measurements reveal that among the three electrodes the glassy carbon electrode with Ruci/TiO2 (1.20% wt. Ru) exhibits the highest activity with a relatively small Tafel slope of 52 mV dec(-1), the highest exchange current density of 0.728 mA cm(-2), and the smallest overpotential of 41 mV at j = 10 mA cm(-2). Furthermore, it demonstrates superior stability in acidic solution with an unaltered onset potential for long term electrochemical measurement. (C) 2018 Elsevier Inc. All rights reserved.