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Öğe A New Strategy for Photo-Electrochemical Reduction of Carbon Dioxide Using a Carbazole-BODIPY Based Metal-Free Catalyst(Wiley-V C H Verlag Gmbh, 2024) Özdemir, Mücahit; Uluçay, Sude; Altınışık, Sinem; Köksoy, Baybars; Yalçın, Bahattin; Koyuncu, SermetIn this study, a cross-linked boron dipyrromethene (BODIPY) photocatalyst containing a carbazole donor group designed for photoelectrocatalytic carbon dioxide (CO2) reduction is synthesized and characterized. The BODIPY-based system, coated onto a platinum surface, is evaluated for its electrochemical and photocatalytic performance under light illumination. Cyclic voltammetry (CV) and chronoamperometry measurements reveals enhanced photocurrent responses, confirming the catalyst's ability to effectively drive CO2 reduction. Gas chromatography/mass spectrometry (GC-MS) analysis identifies the formation of ethanol (C2H5OH) as a major reaction product, showing that its yield increased with extended reaction times. Additionally, the photocatalyst demonstrates remarkable performance with significantly increasing turnover numbers (TON) and turnover frequencies (TOF) over time, indicating stable and sustained catalytic activity. With a Faradaic efficiency of 34.79% at a potential of -1.15 V, this BODIPY system exhibits both high activity and long-term stability. The combination of efficient electron transfer and visible light absorption by the carbazole-BODIPY donor-acceptor structure positions this system as a highly promising candidate for sustainable CO2 conversion applications.Öğe Black-to-Transmissive Electrochromic Switching PEDOT-co-poly(N-ethylcarbazole) via a Sustainable and Facile In Situ Photo(co)polymerization Method(Amer Chemical Soc, 2024) Tabak, Tuğberk; Altınışık, Sinem; Uluçay, Sude; Koyuncu, Sermet; Kaya, KeremIt is a great challenge to obtain black-to-transmissive switches using one type of polymer. Therefore, the color blending/mixing theory has been previously applied by many research groups to produce black-to-transmissive materials (BTMs) through the (electro)chemical copolymerization of several monomers. However, these (electro)chemical copolymerization methods exhibited numerous drawbacks in terms of sustainability. In this work, for the first time, the synthesis of an electrically conductive (bromide-doped) poly(3,4-ethylenedioxythiophene)-poly(N-ethylcarbazole) (PEDOT-co-PECz) copolymer was demonstrated using an in situ and sustainable photopolymerization technique. Spectrally and microscopically characterized copolymers were then deposited onto ITO/glass using spray coating. The copolymer film demonstrated to switch from a black state (L*: 38.16; a: -0.33; b: -2.89) to a transmissive state (L* = 83, a* = -3, b* = -6) with a contrast of 31.6% Delta T at 650 nm in fast response times (2.28-4.38 s). The results highlight the importance of this advanced method for the sustainable and fast fabrication of smart windows.Öğe Electrochromic supercapacitor electrodes based on viologen-derived cross-linked thin films(Elsevier B.V., 2025) Uluçay, Sude; Ha, Neul Gyum; Kortun, Arzu; Altınışık, Sinem; Piravadili Selin; Kwon, Jin Han; Moon, Hong Chul; Koyuncu, SermetViologens are an important class of materials in organic electrochromic technology due to their n-type semiconductor properties and the high color intensity in their radical cation state. Due to their charged structures, viologens are generally ideal molecules for gel-based organic electrochromic devices, but with specific modifications, they can also be employed in thin-film-based electrochromic devices (ECDs). In this study, crosslinking reactions of viologen-based molecules (ALV-X) with various allyl group-containing counterions were conducted on ITO/Glass surfaces in the presence of a tetra-thiol-based crosslinker. The surface roughness of the resulting films varied from 4.64 nm to 8.46 nm depending on the counterion exchange. Electrochemical characterizations of the prepared viologen-based crosslinked electrodes indicated that the LUMO energy levels ranged between −4.267 eV and −4.297 eV. Viologen-based cross-linked thin films with transmittance changes close to 30 % in the visible region, 50 % in the UV region and 20 % in the NIR region with specific capacitances of 0.25 mF cm−2 have been found to be highly suitable materials, especially as cathodic layers in electrochromic/supercapacitor devices. © 2025 Elsevier B.V.Öğe Konjuge viyolojenlerin çapraz bağlı elektrot malzemesi olarak foto-elektrokimyasal co2 indirgeme sistemlerinde kullanımı(Çanakkale Onsekiz Mart Üniversitesi, 2025) Uluçay, Sude; Koyuncu, SermetBu çalışmada, tetraallil fonksiyonlu konjuge viyolojen türevi (TPP-A) sentezlenerek foto-elektrokimyasal CO₂ indirgeme sistemlerinde çapraz bağlı elektrot malzemesi olarak kullanımı araştırılmıştır. Öncelikle 1,3,6,8-tetrabromopiren ve piridin-4-boronik asit esteri kullanılarak tetrapiridin fonksiyonlu piren (TPP) sentezi gerçekleştirilmiş, ardından allil bromür ile reaksiyona sokularak TPP-A elde edilmiştir. Elde edilen malzemenin yapısal ve kimyasal özellikleri FT-IR, ¹H-NMR ve elektrokimyasal karakterizasyon teknikleri ile doğrulanmıştır. TPP-A, platin levha ve TiO₂ kaplı FTO cam yüzeylere çapraz bağlama yöntemiyle kaplanarak tek hücre ve H tipi hücre konfigürasyonlarında foto-elektrokimyasal CO₂ indirgeme deneyleri yapılmıştır. Döngüsel voltametri, kronoamperometri ve elektrokimyasal impedans spektroskopisi sonuçları, çapraz bağlı elektrotların CO₂ indirgeme reaksiyonlarında yüksek etkinlik gösterdiğini ve ışık altında akım yoğunluğunun belirgin şekilde arttığını ortaya koymuştur. Gaz kromatografisi-kütle spektroskopisi (GC-MS) analizleri, CO₂'nin ilk indirgenme basamağı olarak CO oluştuğunu ve nihai ürün olarak etanol elde edildiğini göstermiştir. Elde edilen sonuçlar, konjuge viyolojen bazlı çapraz bağlı elektrotların, görünür ışık altında CO₂'yi değerli kimyasallara dönüştürmede etkili fotokatalizörler olarak kullanılabileceğini göstermektedir.
