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Article Citation - WoS: 17Citation - Scopus: 17Effects of Fluorination and Thermal Shock on the Photocatalytic Activity of Bi2o3< Nanopowders(Elsevier, 2021) Bouziani, Asmae; Park, Jongee; Ozturk, AbdullahFluorinated Bi2O3 (F-Bi2O3) nanopowder was prepared via fluorination followed by thermal shock of alpha-Bi2O3 nanopowder. The XRD, FTIR, SEM, and DRS characterization techniques were employed to investigate the effects of fluorine (F) insertion into the alpha-Bi2O3 host and the thermal shock from different temperatures. The crystal structure, optical and photocatalytic properties of the F-Bi2O3 nanopowders prepared were researched. The XRD results confirmed the substitution of O2- with F-. The FTIR results revealed that the coordination of Bi atoms changed upon F- substitution. The incorporation of F into the alpha-Bi2O3 host and thermal shock did not influence the morphology but modified the band structure of alpha-Bi2O3, leading to a red-shift in the optical absorption edge. Also, the bandgap narrowed from 2.8 eV to 2.6 eV. The density functional theory calculation proved that the F 2p orbitals were positioned in the valence band (VB), resulting in broader and more spread bands for F-Bi2O3. The results suggested that the photoexcited charge carrier mobility in the valence band (VB) and conduction band (CB) are enhanced upon F insertion into alpha-Bi2O3. The photocatalytic efficiency of the synthesized nanopowders was assessed by the degradation of Bromocresol Green (BG) under visible light illumination. Photocatalytic activity improved upon fluorination. The F-Bi2O3 nanopowders thermally shocked from higher temperatures showed negligible photocatalytic performance. The best photocatalytic performance of 70% BG degradation was realized after 180 min visible irradiation for the F-Bi2O3 nanopowder thermal shocked from 500 degrees C.Article Citation - WoS: 30Citation - Scopus: 32Effect of Fluorine Substituted Benzothiadiazole on Electro-Optical Properties of Donor-Acceptor Type Monomers and Their Polymers(Elsevier Sci Ltd, 2020) Cakal, Deniz; Ercan, Yunus Emre; Onal, Ahmet M.; Cihaner, AtillaA series of trimeric monomers bearing thiophene donor units and fluorinated analogues of benzothiadiazole acceptor units was synthesized via donor-acceptor-donor approach and polymerized electrochemically in order to investigate the effect of fluorine atom on electro-optical properties of both monomers and their corresponding polymers. All monomers exhibited solvatochromic and fluorescent properties. The introduction of fluorine atom into the conjugated backbone increased the oxidation potentials. Upon moving from nonfluorinated to fully fluorinated analogues, the oxidation potential shifts anodically from 1.30 V to 1.7 V. As in the case of monomers, the fluorine atom substitution also resulted in a decrease in the HOMO energy level of the corresponding polymers, leading to an increase in the electrochemical band gap energy (1.71-1.97 eV). This result can be attributed to deviations from planarity and also to decrease in the effective conjugation length. The polymeric film also exhibited electrochromic properties under various external potentials. Switching time and coloration efficiency values decreased with increasing number of fluorine atom substitution.
