Browsing by Author "Kaya, S."
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Item Open Access Core–shell magnetic nanoparticles deliver singlet oxygen for mild oxidations: rechargeable, removable, reusable(Royal Society of Chemistry, 2022-02-23) Yıldız, Deniz; Kaya, S.; Türksoy, Abdurrahman; Akkaya, E.U.Singlet oxygen is a useful reactive species. In addition to its role in photodynamic therapy, a variety of synthetically useful reactions can be carried out using singlet oxygen generated by photosensitization. In this work, we present a novel approach for synthetic applications, where singlet oxygen can be generated both via photosensitization and by thermal cycloreversion reaction of a singlet oxygen storage/photo-sensitizer compound on nanoparticles. With this goal in mind, a BODIPY photosensitizer-pyridone conjugate was covalently tethered to silica–iron oxide core–shell nanoparticles. The modified nanoparticles serve as singlet oxygen sources through photosensitization of the BODIPY core, or alternatively, once the pyridone module is transformed into an endoperoxide, they can be used as a chemical source of singlet oxygen under mild conditions in the dark. The nanoparticle-based agent can easily be recovered with a magnet and can be reused repeatedly. We expect ready and convenient availability of singlet oxygen to broaden the scope of reactions for this reactive oxygen species.Item Open Access Hybrid CuFe-CoFe prussian blue catalysts on BiVO4for enhanced charge separation and injection for photoelectrochemical water oxidation(American Chemical Society, 2022-12-26) Usman, E.; Vishlaghi, B.; Akbari, Sina Sadigh; Karadaş, F.; Kaya, S.The utilization of cocatalysts on the photoelectrode surface is a feasible strategy to achieve a high photocurrent density in the photoelectrochemical water oxidation process. The catalysts can enhance the activity by improving the reaction kinetics, retarding charge carrier recombination, or accumulating charge carriers. In this work, we have utilized a CuFe–CoFe Prussian blue (PB) catalyst layer on the BiVO4 photoanode surface to enhance its water oxidation activity. The hybrid catalyst, in which the semiprecious cobalt ions are partially substituted with earth-abundant copper ions, exhibits 56% higher photocurrent density than the CoFe PB-modified BiVO4. We show that photogenerated hole accumulation is present in the CuFe PB layer, which results in higher charge extraction from the BiVO4 surface. The CoFe PB layer on top of the CuFe one facilitates the charge transfer due to its catalytic activity toward the oxygen evolution reaction (OER).Item Open Access Imaging of intracellular singlet oxygen with bright BODIPY dyes(Elsevier Ltd, 2021-04) Kaya, S.; Kwon, N.; Kim, G.; Bila, Jose Luis; İsmaiel, Yahya A.; Yoon, J.; Seven, Özlem; Akkaya, E.Singlet oxygen is a cytotoxic reactive species which is involved in the photodynamic therapy of cancer. It is also known to be produced endogenously in most eukaryotic cells and implicated in many biochemical processes, including apoptotic response. We now report that Bodipy based fluorescent dyes with singlet oxygen reactive modules, signal the intracellular generation of singlet oxygen through photosensitization. We believe long wavelength probes of singlet oxygen, based on this approach will be highly valuable.Item Open Access Strong light–matter interactions in Au plasmonic nanoantennas coupled with Prussian blue catalyst on BiVO4 for photoelectrochemical water splitting(Wiley-VCH Verlag, 2020) Ulusoy-Ghobadi, Türkan Gamze; Ghobadi, Amir; Soydan, Mahmut Can; Vishlaghi, M. B.; Kaya, S.; Karadaş, Ferdi; Özbay, EkmelA facial and large‐scale compatible fabrication route is established, affording a high‐performance heterogeneous plasmonic‐based photoelectrode for water oxidation that incorporates a CoFe–Prussian blue analog (PBA) structure as the water oxidation catalytic center. For this purpose, an angled deposition of gold (Au) was used to selectively coat the tips of the bismuth vanadate (BiVO4) nanostructures, yielding Au‐capped BiVO4 (Au‐BiVO4). The formation of multiple size/dimension Au capping islands provides strong light–matter interactions at nanoscale dimensions. These plasmonic particles not only enhance light absorption in the bulk BiVO4 (through the excitation of Fabry–Perot (FP) modes) but also contribute to photocurrent generation through the injection of sub‐band‐gap hot electrons. To substantiate the activity of the photoanodes, the interfacial electron dynamics are significantly improved by using a PBA water oxidation catalyst (WOC) resulting in an Au‐BiVO4/PBA assembly. At 1.23 V (vs. RHE), the photocurrent value for a bare BiVO4 photoanode was obtained as 190 μA cm−2, whereas it was boosted to 295 μA cm−2 and 1800 μA cm−2 for Au‐BiVO4 and Au‐BiVO4/PBA, respectively. Our results suggest that this simple and facial synthetic approach paves the way for plasmonic‐based solar water splitting, in which a variety of common metals and semiconductors can be employed in conjunction with catalyst designs.