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    Morphological, microstructural and photocatalytic characterization of undoped and Ni, Co doped Fe2O3 particles synthesized by sonochemical method
    (Scientific & Technical Research Council Turkey-TUBITAK, 2022) Kaya, Elif Emil; Evren, Burak; Erdöl, Zeynep; Ekinci, Duygu; İpekoğlu, Mehmet; Özenler, Sibel
    In this study, an abundant and eco-friendly photocatalytic material, Fe2O3 particles were synthesized by sonochemical method. Morphological and microstructural investigations of synthesized undoped and Ni, Co-doped Fe2O3 particles were performed. The effect of particle morphology and microstructure on its photocatalytic performance was further investigated. Comparative studies for evaluating particle crystallite sizes were conducted by Williamson-Hall (W-H) method and modified Debye-Scherrer (MDS). Crystallite sizes and lattice strains of Fe2O3 induced by process parameters were calculated by W-H method based on uniform deformation model (UDM). The crystallite sizes of the synthesized powders were calculated in the range of 200 nm and 76 nm by Williamson-Hall analysis. In addition to structural investigation, dislocation density of the synthesized particles was calculated by Williamson-Smallman relation. Afterwards, photocatalytic performance of Fe2O3 particles was investigated in detail. The photodegradation of methylene blue solutions in the presence of light in 20 min with samples 3,4, and 5 in 20 min were 0.937, 0.896, and 0.855, respectively. Moreover, the photodegradation of methylene blue solution with sample 5 for 15, 30, and 45 min were 0.9, 0.828, and 0.757, respectively. A photocatalytic activity of 24.25% has been observed under optimum conditions for the time interval of 45 min.
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    Öğe
    SYNTHESIS AND CHARACTERIZATION OF MWCNT-SUPPORTED PBI MEMBRANES FOR HT-PEM FUEL CELLS
    (International Association for Hydrogen Energy, IAHE, 2022) Görüryılmaz, Mehmet Turan; Özenler, Sibel; Zeytuncu, Bihter; Karatepe, Nilgün
    Polybenzimidazole (PBI) membranes are highly sought after for HT-PEMFCs due to their thermal stability, mechanical strength and protonic conductivity. In this study, PBI polymer and the membranes were synthesized for HT-PEMFC applications. Then, the polymer was characterized by using NMR and TG analyses. All the characteristic peaks were observed in the NMR results and PBI polymer decompose around 550 °C. After the synthesis, pristine and multi-walled carbon nanotube (MWCNT) supported membranes were prepared, doped with phosphoric acid and characterized by using TGA, FT-IR, XRD, SEM and EIS tests. The characteristic bonds of the polymer for both undoped and doped membranes were seen in FT-IR results. XRD results showed the semi-crystalline structure of the polymer. SEM results enabled to observe the homogeneous dispersion of the MWCNTs within the membrane. Finally, EIS tests were carried out in anhydrous conditions. The conductivities were obtained for pristine PBI membrane as 0.0518 S/cm, 0.0667 S/cm and 0.0895 S/cm, respectively. For the 0.5wt% PBI/MWCNT membrane, they were calculated as 0.0401 S/cm, 0.0586 S/cm and 0.0613 S/cm for 120 °C, 140 °C and 160 °C, respectively. For the 1wt% PBI/MWCNT membrane, slightly higher conductivities were obtained as 0.0429 S/cm, 0.0621 S/cm and 0.0655 S/cm for the temperatures 120 °C, 140 °C and 160 °C, respectively. © 2022 Proceedings of WHEC 2022 - 23rd World Hydrogen Energy Conference: Bridging Continents by H2. All rights reserved.