Researcher:
Munir, Shamsa

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Researcher

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Shamsa

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Munir

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Munir, Shamsa

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Now showing 1 - 2 of 2
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    Publication
    Electrocatalytic reduction of CO2 to produce higher alcohols
    (Royal Soc Chemistry, 2018) N/A; N/A; N/A; Department of Chemistry; Department of Chemistry; Munir, Shamsa; Varzeghani, Amir Rahimi; Kaya, Sarp; Researcher; PhD Student; Faculty Member; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); N/A; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 116541
    Electrodeposited and thermally oxidized copper surfaces have been documented in recent years to produce simple alcohols. In this work, we endeavored to study the electrochemical reduction of CO2 at different electrodes prepared via the electrodeposition method, namely, Cu-Cu2O, Cu-Cu2O-ZnO, and Cu-ZnO. In addition, thermally oxidized Cu (Cu-TO) was also investigated. C1, C2, and C3 species were produced on Cu-Cu2O-ZnO, Cu-Cu2O, and Cu-ZnO. The highest faradaic efficiency (FE of 97.4%) of the liquid products (methanol, formate, n-propanol, acetone) was evidenced on Cu-ZnO. The formation of C3 species with high FE on the Cu-ZnO electrode is attributed to the fast C-C-C coupling at the Cu-Zn interface. on thermally oxidized Cu, the total FE of the liquid products (methanol, formate, ethanol, acetate, n-propanol) was found to be 58.51%, which is considerably closer to the already reported values for these electrodes. Moreover, the Cu-Cu2O-ZnO electrode revealed selectivity toward methanol production. Detailed morphological and elemental analyses of the electrode, performed using XPS, Raman spectroscopy, and FESEM, as well as activity measurements to obtain an insight into the mechanistic pathways, reveal that C-C coupling is favored on Cu-0 sites rather than Cu2O. Moreover, methanol formation seems to proceed via O coordination of CO2 to Cu-Cu2O surface having (100) facets, whereas C coordination is favored on Cu-TO with (111) exposed faces, resulting in Cu-0 sites. The localized formation of ZnO nanoflowers was observed on Cu-ZnO electrodes after the electrochemical reduction of CO2, which is attributed to the mechanistic pathway involving chemical steps, leading to the formation of C3 species.
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    Publication
    The significance of the local structure of cobalt-based catalysts on the photoelectrochemical water oxidation activity of BiVO4
    (Pergamon-Elsevier Science Ltd, 2021) Harfouche, Messaoud; Ogasawara, Hirohito; N/A; N/A; N/A; N/A; N/A; N/A; N/A; Department of Chemistry; Department of Chemistry; Barzgarvishlaghi, Mahsa; Kahraman, Abdullah; Apaydın, Sinem; Usman, Emre; Aksoy, Dilan; Balkan, Timuçin; Munir, Shamsa; Kaya, Sarp; PhD Student; PhD Student; Master Student; Master Student; PhD Student; Other; Researcher; Faculty Member; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; N/A; N/A; College of Sciences; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); N/A; N/A; N/A; N/A; N/A; N/A; N/A; 116541
    The local structures of the water oxidation catalysts play an important role in reaction kinetics and the performance of the photoanodes. In this study, we deposited cobalt-based catalysts on nanoporous BiVO4 with controlled thicknesses by atomic layer deposition (ALD). Despite the similar oxidation states of cobalt in all depositions, different water oxidation activities in neutral pH conditions were observed. A dramatic photocurrent raise, lowered kinetic overpotential, and smaller charge transfer resistance across the photoanode/electrolyte interface were achieved when a uniform ultrathin Co(OH)(2) layer was formed on BiVO4. Photocurrent density for water oxidation showed a 95% enhancement at 0.6 V vs. RHE when the catalyst was in the form of Co(OH)(2), while an 80% increase was obtained for CoO. Ideal coordination of Co(OH)(2) on hydroxylated BiVO4 surface assists the charge transfer between the electrolyte and BiVO4 without increasing surface recombination. The results of this study emphasize the importance of controlling the local structure of the catalysts in the performance of the water splitting photoanodes.