Yazar "Unal, Fatma Aydin" seçeneğine göre listele

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    Synthesis and characterization of (La, Cu) co-doped CeO2 nanomaterials used as electrolyte material in SOFC applications
    (Springer Heidelberg, 2023) Unal, Fatma Aydin
    This paper, it is aimed that nanometer-sized powders can be successfully prepared by using the sol-gel process so that sintering temperatures can be reduced and they can be used as suitable electrolyte candidate materials for medium-temperature SOFC applications. Fort his, bare CeO2 (cerium dioxide), which has not yet been encountered in the literature, and La,Cu co-doped CeO2 nanoparticles with different molar ratios (1%, 5%, and 10%) were synthesized as electrolyte material using the sol-gel method for intermediate-temperature solid oxide fuel cells (IT-SOFCs) applications. The synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), UV-Vis spectroscopy, and particle size analysis techniques. In order to examine the effect of doping, the structural, morphological, and optical properties of bare cerium oxide and doped cerium oxide powders were compared. With the doping process, reductions in average particle sizes were observed, and it was determined that the sample with the lowest average particle size was 5% (La, Cu) co-doped CeO2. It has been confirmed by XRD and SEM/EDX that bare CeO2 and co-doped CeO2 powder synthesized have been successfully achieved by the sol-gel technique. The results show that the La,Cu co-doped CeO2 sample is promising as an electrolyte material in SOFC applications.
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    Öğe
    Synthesis and characterization of the doped/co-doped SnO2 nanoparticles by the sol-gel method
    (Wiley, 2025) Unal, Fatma Aydin
    Tin oxide (SnO2) is one of the important semiconductors used in the application of solar cells because of its chemical-mechanical stability and wide band gap. These properties are very important for the performance development and photoanode optimization of a dye-sensitized solar cell (DSSC). However, the low conduction band value of SnO2 reduces the photovoltaic efficiency, which limits the application of DSSC. Therefore, the doping strategy was used to increase the sensitivity to the visible light spectrum and change the light absorption properties of SnO2. In this paper, pure SnO2, Ag/SnO2, Pt/SnO2, and Pt/Ag/SnO2 nanoparticles were synthesized at the nanoscale by a simple chemical sol-gel method. To characterize the structure, morphological/chemical properties, optical properties, and surface properties of the synthesized SnO2 nanoparticles, X-Ray Diffraction (XRD), ultraviolet-visible, Brunauer-Emmett-Teller, Scanning Electron Microscopy (SEM)/Energy Dispersive X-Ray Spectroscopy (EDX), Transmission Electron Microscopy (TEM), and particle size analysis were respectively used. XRD results showed that the crystal sizes varied between 8.8 and 12.2 nm depending on the doping. Doping processes resulted in reductions in particle sizes. Optical studies resulted in decreases in the band gap with the doping process. The conclusions obtained have shown that Ag doping, and Pt-Ag co-doping can be promising for use as photoanode materials in semiconductor technology and especially in DSSC applications.
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    Öğe
    Synthesis, characterization, photocatalytic application of Gd/K co-doped ZnO
    (Wiley, 2024) Unal, Fatma Aydin; Unal, Murat; Ataser, Tugce; Ozcelik, Sueleyman
    In this paper, we introduce the synthesis of undoped ZnO and 5 wt % Gd/K co-doped ZnO compounds to improve photocatalytic activity. Undoped ZnO particles and Gd/K co-doped ZnO particles were synthesized by the sol-gel method. The samples were studied by X- Ray Diffraction (XRD), Scanning Electron Microscopy (SEM)/energy dispersive X-ray (EDX), Ultraviolet Visible Spectroscopy (UV-Vis), Brunauer-Emmett-Teller (BET), and particle size analysis. Then tehir photocatalytic activities were tested. SEM micrographs showed that the particle size was in the sub-micrometer or nanometer range. Particle size analysis revealed that the mean size was closer to the micrometer range. The specific surface area of the powder was obtained quite low in accordance with the larger particle size. The photocatalytic activity of 5% Gd/K co-doped ZnO was compared with undoped ZnO in the degradation methyl blue. When their photocatalytic activities were examined, Gd/K co-doped ZnO showed & SIM;66% degradation at 60 min, while undoped ZnO showed & SIM;52% degradation at the same time. image