Browsing by Author "Chalil Oglou, Ramadan"

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    A dormant reagent reaction-diffusion method for the generation of Co-Fe Prussian Blue analogue periodic precipitate particle libraries
    (Wiley-VCH GmbH, 2023-08-25) Tootoonchian, Pedram; Kwiczak-Yiğitbaşı, Joanna; Turab Ali Khan, Muhammad; Chalil Oglou, Ramadan; Holló, G.; Karadaş, Ferdi; Lagzi, I.; Baytekin, Bilge
    Liesegang patterns that develop as a result of reaction-diffusion can simultaneously form products with slightly different sizes spatially separated in a single medium. We show here a reaction-diffusion method using a dormant reagent (citrate) for developing Liesegang patterns of cobalt hexacyanoferrate Prussian Blue analog (PBA) particle libraries. This method slows the precipitation reaction and produces different-sized particles in a gel medium at different locations. The gel-embedded particles are still catalytically active. Finally, the applicability of the new method to other PBAs and 2D systems is presented. The method proves promising for obtaining similar inorganic framework libraries with catalytic abilities. © 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.
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    Manipulating intermetallic charge transfer for switchable external stimulus-enhanced water oxidation electrocatalysis
    (John Wiley and Sons Inc, 2023-10-26) Chalil Oglou, Ramadan; Ulusoy Ghobadi, Türkan Gamze; Hegner, F. S. .; Galán-Mascarós, J. R.; López, N; Özbay, Ekmel; Karadaş, Ferdi
    Electrocatalytic processes involving the oxygen evolution reaction (OER) present a kinetic bottleneck due to the existence of linear-scaling relationships, which bind the energies of the different intermediates in the mechanism limiting optimization. Here, we offer a way to break these scaling relationships and enhance the electrocatalytic activity of a Co−Fe Prussian blue modified electrode in OER by applying external stimuli. Improvements of ≈11 % and ≈57 % were achieved under magnetic field (0.2 T) and light irradiation (100 mW cm−2), respectively, when working at fixed overpotential, η=0.6 V at pH 7. The observed enhancements strongly tie in with the intermetallic charge transfer (IMCT) intensity between Fe and Co sites. Density Functional Theory simulations suggest that tuning the IMCT can lead to a change of the OER mechanism to an external stimuli-sensitive spin crossover-based pathway, which opens the way for switchable electrocatalytic devices.
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    “Plug and Play” photosensitizer–catalyst dyads for water oxidation
    (American Chemical Society, 2022-04-28) Chalil Oglou, Ramadan; Ulusoy Ghobadi, T. Gamze; Özbay, Ekmel; Karadaş, Ferdi
    We present a simple and easy-to-scale synthetic method to plug common organic photosensitizers into a cyanide-based network structure for the development of photosensitizer-water oxidation catalyst (PS-WOC) dyad assemblies for the photocatalytic water oxidation process. Three photosensitizers, one of which absorbs red light similar to P680 in photosystem II, were utilized to harvest different regions of the solar spectrum. Photosensitizers are covalently coordinated to CoFe Prussian blue structures to prepare PS-WOC dyads. All dyads exhibit steady water oxidation catalytic activities throughout a 6 h photocatalytic experiment. Our results demonstrate that the covalent coordination between the PS and WOC group not only enhances the photocatalytic activity but also improves the robustness of the organic PS group. The photocatalytic activity of “plug and play” dyads relies on several structural and electronic parameters, including the position of the energy levels of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the PS with respect to the HOMO level of the catalytic site, the intensity and wavelength of the absorption band of the PS, and the number of catalytic sites.
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    Rational design of an acceptor-chromophore-relay-catalyst tetrad assembly for water oxidation
    (Royal Society of Chemistry, 2023-12-25) Chalil Oglou, Ramadan; Ulusoy Ghobadi, T. Gamze; Saylam, A.; Bese, D.; Bese, C.; Yağlıoğlu, Halime Gül; Özçubukçu, S.; Özbay, Ekmel; Karadaş, Ferdi