Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 5Citation - Scopus: 6Formation of Monolithic Srtio3-Tio2 Ceramic Heterostructures by Reactive Hydrothermal Sintering(Elsevier, 2023) Karacasulu, Levent; Kartal, Uğur; İçin, Öykü; Bortolotti, Mauro; Biesuz, Mattia; Ahmetoğlu, Çekdar VakıfIn a one-pot approach, monolithic SrTiO3-TiO2 ceramic heterostructures were obtained using the reactive hydrothermal liquid phase densification (rHLPD). Structural, morphological, and photocatalytic properties of the obtained ceramics were analyzed. The relative density of the formed components reached about 80% with reaction time, temperature, and NaOH concentration variation. It was observed via Rietveld refinement that there was no XRD detectable phase other than TiO2 and SrTiO3 in the final structure. The monolithic SrTiO3-TiO2 ceramics obtained by hydrothermal reaction at 120 °C for 24 h in 1 M NaOH concentration showed a dielectric constant being around 500, and the dielectric loss was below 0.25 at frequencies higher than 10 kHz. The SrTiO3-TiO2 heterostructured monoliths having only 20 vol% total porosity and low specific surface area, demonstrated ∼60% efficiency (in 5 h) in degrading Methylene Blue photo-catalytically. © 2023 Elsevier LtdArticle Citation - WoS: 4Citation - Scopus: 5The Effect of Geometrical Characteristics of Tio2 Nanotube Arrays on the Photocatalytic Degradation of Organic Pollutants(Springer, 2023) Kartal, Uğur; Uzunbayır, Begüm; Doluel, Eyyüp Can; Yurddaşkal, Metin; Erol, MustafaHighly ordered TiO2 nanotube arrays (TNAs) were fabricated by electrochemical anodization under varying durations and voltages. The effects of the anodizing parameters on geometrical properties were investigated. The results showed that as the anodizing time increased from 15 to 45 min, the length of the nanotubes increased, but there was no change in their diameter, hence the surface area increased while the open porosity did not change. When the effect of the anodizing voltage was examined, it was observed that both the length and diameter increased as the voltage increased from 15 to 45 V. Thus, a significant increase in open porosity and surface area was observed. The UV-Vis spectrophotometer was used to evaluate the effects of all geometrical characteristics on the photodegradation of methylene blue (MB). The results showed that the anodizing parameters were highly effective on the photocatalytic degradation of MB. With the decrease of the anodizing voltage, the photocatalytic activity increased because of the geometrical characteristics of TNAs. Accordingly, TNAs with the surface area of 25 m(2)/g and the open porosity of 35% obtained by anodizing for 45 min at 15 V showed the highest photocatalytic activity with a degradation efficiency of similar to 81% in 7 h.Article Citation - WoS: 9Citation - Scopus: 9Zno Nanostructures for Photocatalytic Degradation of Methylene Blue: Effect of Different Anodization Parameters(Springer, 2022) Öksüz, Ahmet Emrecan; Yurddaşkal, Metin; Kartal, Uğur; Dikici, Tuncay; Erol, MustafaIn this paper, the photocatalytic activity of ZnO nanostructures formed by anodization method with different parameters was investigated. The synthesis of ZnO nanostructures with different morphology by varying anodic oxidation parameters containing electrolytes, molarity, voltage, and duration was analyzed. ZnO nanostructures were prepared through different parameters consisting of six samples. The produced ZnO nanostructures were investigated by using X-ray diffraction, scanning electron microscopy, diffuse reflectance spectroscopy, and UV-Vis spectrophotometer. It was found that the morphology of ZnO structures was formed as nanorods, needle-like, flower-like, heterogeneous, and homogeneous of mixed structures. ZnO nanostructures were identified by matching X-Ray diffraction peaks due to the international center for diffraction data database. Experiments on photocatalytic degradation of methylene blue demonstrated that the photocatalytic activity of ZnO samples. The best photocatalytic performance was observed by the sample anodized for an hour in 0.05 M of KHCO3 electrolytes with 40 V electrical potential. It was observed that the removal of methylene blue increased 3 times (photocatalytic degradation efficiency similar to 31% for methylene blue vs similar to 90% by the best sample) thanks to the obtained ZnO nanostructured photocatalysts. The results showed that an increment of the voltage has a significant effect on the photocatalytic activity of ZnO while keeping other parameters including molarity, time, and electrolyte type constant.Article Citation - WoS: 30Energy Harvesting Nanogenerators: Electrospun Β-Pvdf Nanofibers Accompanying Zno Nps and Zno@ag Nps(Elsevier, 2021) Zeyrek Ongun, Merve; Oğuzlar, Sibel; Kartal, Uğur; Yurddaşkal, Metin; Cihanbeğendi, Özge; Zeyrek Ongun, Merve; Oğuzlar, Sibel; Kartal, Uğur; Yurddaşkal, Metin; Cihanbeğendi, ÖzgeThis paper aims to demonstrate that synthesized nano-scale zinc oxide (ZnO) and different concentrations (1, 3 and 5 wt%) of silver-doped zinc oxide (ZnO@Ag) nanoparticles (NPs), which were employed to enhance the piezoelectric content of the electrospun β-phase poly (vinylidene fluoride) PVDF nanofibers, may be an alternative for usual semiconductor dopant. The structural and morphological properties of all the synthesized materials were investigated. The impedance and the capacitance values of the manufactured nanogenerators were also investigated at room temperature. The peak-to-peak amplitude output voltage data of ZnO NPs and ZnO@Ag NPs doped PVDF-based electrospun nanomats were measured using digital oscilloscope while a finger-tapping action at a frequency of ∼1 Hz was conducted. The electrical output of 5 wt% Ag-doped ZnO-based β-PVDF nanofibers increased from 0.5 to 1.5 V compared to undoped β-PVDF samples. These findings have a wide range of auspicious applications, including energy harvesting devices, portable electronic systems, and self-powered electrical gadgets that can be worn.