Researcher:
Alemdar, Sıla

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Master Student

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Sıla

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Alemdar

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Alemdar, Sıla

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Now showing 1 - 2 of 2
  • Placeholder
    Publication
    Reduced graphene oxide/few-layer phosphorene binary heterojunctions as metal-free photocatalysts for the sustainable photoredox C-H arylation of heteroarenes
    (American Chemical Society, 2024) Turbedaroglu, Özge; Kılıç, Haydar; Department of Chemistry; Department of Chemistry; Kubanaliev, Temirlan; Alemdar, Sıla; Eroğlu, Zafer; Metin, Önder; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; College of Sciences
    Herein, we report the fabrication of few-layer phosphorene (FLP)/reduced graphene oxide (rGO) binary heterojunctions as metal-free photocatalysts for the direct C-H arylation of heteroarenes under visible light irradiation. The FLP/rGO heterojunctions were prepared by mixing the solutions of well-exfoliated rGO and FLP nanosheets in an ultrasonic bath, resulting in a well-coupled structure between rGO and FLP. Characterization revealed enhanced stability, charge separation efficiency, and extended charge transfer ability in the heterojunction compared to the pristine materials. Studying different FLP to rGO mass ratios helped to find the optimum synergy where the materials exhibited the highest photocatalytic activity, and the optimized FLP/rGO catalyst with 30% FLP yielded the desired products with the highest photocatalytic efficiency in the C-H arylation of aryl diazonium salts and heteroarenes (24 examples in total). Notably, aryl diazonium salts with electron-withdrawing groups achieved high yields in the range of 68-90%. The FLP/rGO heterojunctions were successfully applied in synthesizing dantrolene, a commercially available drug, yielding 41% yield for C-H arylation and 90% yield for subsequent synthesis. The heterojunctions demonstrated excellent reusability, maintaining high catalytic activity over five cycles with only a 6% decrease in their initial activity. Mechanistic studies suggest a plausible single electron transfer mechanism wherein photogenerated electrons are transferred from FLP/rGO to aryl diazonium salts, forming biaryl radical intermediates and subsequent products. Overall, the FLP/rGO binary heterojunctions have been demonstrated to be efficient and sustainable metal-free photocatalysts for C-H arylation reactions, showcasing a broad substrate scope and potential applications in synthetic chemistry and pharmaceutical synthesis.
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    Publication
    The rational design of a graphitic carbon nitride-based dual S-scheme heterojunction with energy storage ability as a day/night photocatalyst for formic acid dehydrogenation
    (Elsevier Science Sa, 2022) Department of Physics; Department of Computer Engineering; N/A; Department of Chemistry; Department of Physics; Department of Computer Engineering; Department of Chemistry; Altan, Orhan; Altıntaş, Elvin; Alemdar, Sıla; Metin, Önder; Other; Researcher; Master Student; Faculty Member; College of Sciences; College of Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; N/A; 46962
    Photocatalytic formic acid dehydrogenation (FAD) has been regarded as one of the most promising methods of producing H2 in a sustainable manner. In the photocatalytic FAD reaction, photogenerated holes play an important role in the reaction mechanism and thus in the efficiency of photocatalysts. However, the design of photocatalytic systems capable of generating high hole potential without compromising the reducing ability of the photocatalyst is extremely rare for the FAD reaction. In this respect, we report herein a novel and highly efficient heterojunction photocatalyst composed of 2D graphitic carbon nitride, 2D MnO2, 1D MnOOH, and 0D PdAg alloy nanoparticles, denoted as GCN/MnO2/MnOOH-PdAg, that can create high reduction and oxidation potentials via a dual S-scheme heterojunction. The photocatalysts exhibited a superb photocatalytic activity in the FAD with a record turnover frequency (TOF) of 3919 h-1 under visible light irradiation, which was 6-, 5.2and 24-times greater than those of GCN-PdAg, GCN/MnO2-PdAg, and MnO2/MnOOH-PdAg heterojunctions, respectively. The structure and dual S-scheme mechanism of the photocatalyst have been clearly demonstrated by extensive instrumental analysis, radical trapping tests, and scavenger experiments. More importantly, it was discovered that the presented photocatalyst continued to function with comparable activity in dark for a prolonged time using the same photocatalytic mechanism. The activity of the photocatalyst in dark was attributed to the utilization of electrons stored on Mn2O3, which was detected as a 4-5 nm thick layer on the surface of MnOOH nanorods. This study, in addition to being the first example of both a "day/night photocatalyst" for FAD with an S-scheme mechanism, also demonstrates for the first time the boosting of FAD via a dual S-scheme heterojunction photocatalyst.