Researcher:
Yılmaz, Seda

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PhD Student

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Seda

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Yılmaz

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Yılmaz, Seda

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2022 - 20234

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    Enhanced photoelectrochemical activity of magnetically modified TiO2 prepared by a simple ex-situ route
    (Springer, 2022) Kuyumcu, Ozge Kerkez; Bayazit, Sahika Sena; Akyuz, Duygu; Koca, Atif; N/A; N/A; Yılmaz, Seda; PhD Student; PhD Student; N/A; N/A; N/A; N/A
    Modified TiO2 nanocomposites have been recognized as attractive photocatalytic materials in solar energy conversion. The aim of this study is to enhance the photoelectrochemical performance under visible light region by magnetically modified TiO2 nanocomposites (Fe3O4/TiO2 and NiFe2O4/TiO2) prepared by a simple ex-situ non-thermal route. The magnetic TiO2 nanocomposites were characterized by X-ray diffraction (XRD), UV-Vis diffuse reflectance spectra (DRS), photoluminescence spectroscopy (PL), transmission electron microscopy (TEM), vibrational scanning magnetometry (VSM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Photoelectrochemical analysis was performed; chronoamperometry and Mott-Schottky curves were obtained. Results indicated that these non-noble, low-cost photocatalysts have shown the desired features; NiFe2O4/TiO2 have a suitable band gap to harvest visible range of solar light; they have reduced electron-hole recombination; and it is magnetically separable from reaction media. The most promising nanocomposite was found as NiFe2O4/TiO2 with a maximum photocurrent density 132 mu A cm(-2). The possible mechanism accounting for the improved photoelectrochemical performance of NiFe2O4/TiO2 is proposed.
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    Enhanced hydrogen evolution by using ternary nanocomposites of mesoporous carbon nitride/black phosphorous/transition metal nanoparticles (m-gcn/bp-m; m = co, ni, and cu) as photocatalysts under visible light: a comparative experimental and theoretical study
    (Elsevier, 2022) Acar, Eminegul Genc; Yanalak, Gizem; Aslan, Emre; Kilic, Murat; Patır, İmren Hatay; N/A; N/A; Department of Chemistry; Yılmaz, Seda; Metin, Önder; PhD Student; Faculty Member; Department of Chemistry; N/A; N/A; College of Sciences; N/A; N/A; 46962
    The effect of first-row transition metal nanoparticles as co-catalysts on the activity of mesoporous graphitic carbon nitride (m-gCN) and black phosphorous (BP) heterojunctions (m-gCN/BP) in the photocatalytic hydrogen evolution reaction (HER) is investigated comparatively. Three m-gCN/BP-M (M: Co, Ni, and Cu) ternary nanocomposites were prepared via wetness impregnation and chemical reduction of metal precursors on as-prepared m-gCN/BP binary heterojunctions. The photocatalytic HER activities of m-gCN, m-gCN/BP, m-gCN/BP-Ni, mgCN/BP-Co, and m-gCN/BP-Cu nanocomposites were determined to be 0.233, 0.330, 0.442, 0.326, and 0.223 mmol g-1 h-1, respectively, under visible light illumination. These results revealed that type of transition metal NPs as co-catalysts have considerable effect on the activity of m-gCN/BP heterojunctions in the photocatalytic HER, among which m-gCN/BP-Ni is the best one. The DFT calculations performed on the nanocomposites revealed that m-gCN/BP-Ni possesses the lowest band gap and the highest visible light absorption resulting in the highest photocatalytic activity in HER.
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    Metal doped black phosphorus/molybdenum disulfide (BP/MoS2eY (Y: Ni, Co)) heterojunctions for the photocatalytic hydrogen evolution and electrochemical nitrite sensing applications
    (Elsevier Ltd, 2023) Yanalak, G.; Bas, S. Z.; Patir, I. H.; Department of Chemistry; N/A; Department of Chemistry; Eroğlu, Zafer; Yılmaz, Seda; Metin, Önder; Researcher; PhD Student; Faculty Member; Department of Chemistry; College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 46962
    Recently, 2D semiconductor-based heterojunctions emerge as a focal point of intensive research owing to their unique properties, including efficient charge separation and large interface areas. Herein, Ni or Co-doped black phosphorus/molybdenum disulfide (BP/MoS2–Y (Y: Ni, Co)) heterojunctions fabricate for photocatalytic H2 evolution and electrochemical nitrite sensor. Compared to the BP/MoS2, the BP/MoS2–Ni and BP/MoS2–Co exhibit enhanced H2 performance, as 6.4139 mmol h−1 g−1 and 7.4282 mmol h−1 g−1, respectively, in the presence of Eosin-Y (λ ≥ 420 nm). Furthermore, BP/MoS2–Co applies as an electrocatalyst on a GCE for the electrochemical detection of nitrite. To optimize the nitrite sensing performance of BP/MoS2–Co, the effect of the pH, amount of material, scan rates, and other conditions study in detail. The BP/MoS2–Co displays a linear response within the range of 100–2000 μM with a detection limit of 4.1 μM for DPV. This work can offer an opportunity for hydrogen systems as well as electrochemical sensor applications. © 2022 Hydrogen Energy Publications LLC
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    Transition metal (Ni, co)-doped graphitic carbon nitride/MoS2 heterojunctions as efficient photocatalysts for hydrogen evolution reaction under visible light
    (Wiley, 2022) Patır, İmren Hatay; Yanalak, Gizem; Aslan, Emre; N/A; N/A; Department of Chemistry; Yılmaz, Seda; Eroğlu, Zafer; Metin, Önder; PhD Student; Researcher; Faculty Member; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; N/A; College of Sciences; N/A; N/A; 46962
    New photocatalysts comprising the 2D/2D heterojunction of graphitic carbon nitride (gCN) and molybdenum disulfide (MoS2) semiconductors doped with nickel (Ni) or cobalt (Co), denoted as gCN/MoS2-M (M: Ni, Co), were fabricated for the photocatalytic hydrogen evolution reaction (HER) under visible light illumination. First, the binary gCN/MoS2 heterojunctions were fabricated by using an in-situ solvothermal method and then they were doped with Ni or Co via a chemical reduction method. The photocatalytic HER experiments revealed that the prepared gCN/MoS2-M (M: Ni, Co) photocatalysts showed enhanced HER activities and stabilities compared to pristine gCN and binary gCN/MoS2 heterojunctions. Total H-2 productions of 5924 mu mol g(cat)(-1) and 5159 mu mol g(cat)(-1) in 8 hours were provided by using gCN/MoS2-Ni and gCN/MoS2-Co photocatalysts, respectively, under visible light illumination. The detailed structural characterization and examination of optical properties of gCN/MoS2-M (M: Ni, Co) photocatalysts revealed that their enhanced photocatalytic activities were attributed to the formation of 'type-I' 2D/2D heterojunction between gCN and MoS2 semiconductors and the creation of S-deficient MoS2 nanostructures after Ni or Co doping, which promoted the separation of the photogenerated electron-hole pairs, the charge mobility, and the visible light absorption.