Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4719
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Article Citation - WoS: 3Citation - Scopus: 4A Facile Method for Boosting the Graphitic Carbon Nitride's Photocatalytic Activity Based on 0d/2d S-Scheme Heterojunction Nanocomposite Architecture(Elsevier, 2024) Kahraman, Zeynep; Kartal, Uğur; Gent, Aziz; Alp, EmreGraphitic carbon nitride (g-C 3 N 4 ) has received significant interest as a metal -free photocatalyst. The S -scheme photocatalytic system has great potential to improve the charge separation in semiconductor photocatalysts. In this study, we have fabricated non-toxic and low-cost photocatalytic nanocomposites of 0D/2D S -scheme heterojunction composed of iron oxide and graphitic carbon nitride by a facile method. The developed facile method provides a sustainable way with a high atom economy to further enhance the photocatalytic performance of exfoliated g-C 3 N 4 . The 0D -iron oxide/2D-C 3 N 4 exhibited nearly 10 times better than bulk g-C 3 N 4 and almost 60 % better than exfoliated g-C 3 N 4 under simulated solar light irradiation. The experimental results demonstrated that the effective charge -carrier mechanism led to an improved generation of reactive oxygen species (ROSs), resulting in an impressive photocatalytic performance. A serial photocatalytic test was also conducted to understand photocatalytic reaction mechanisms with various scavengers.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: 12Citation - Scopus: 12Dye Removal by Polymer Derived Ceramic Nanobeads(Elsevier, 2021) İçin, Öykü; Ahmetoğlu, Çekdar VakıfEmulsion processed polymer derived ceramic (PDC) nanobeads are used for Methylene Blue dye removal from aqueous solutions. The PDC nanobeads, produced at 600 degrees C and 1200 degrees C pyrolysis, are subsequently coated with titania (anatase). Titania-coated nanobeads show less than 35%, i.e., limited dye adsorption capability in dark. Instead, enhanced total removal efficiency (similar to 97%) is obtained when the initial adsorption is succeeded by photodegradation under UV. Direct reusability tests show that even after the third cycle, very high regeneration efficiencies being above 92% are observed for titania-coated nanobeads.Article Citation - WoS: 19Citation - Scopus: 22Enhanced Methylene Blue Removal Efficiency of Tio2 Embedded Porous Glass(Elsevier Ltd., 2021) Ertuş, E.Burak; Vakıfahmetoğlu, Çekdar; Öztürk, AbdullahA porous glass (PG) embedded with titanium dioxide (TiO2) was produced via impregnation of the PG with Titanium (IV) Isopropoxide solution followed by crystallization. N2 sorption analyses revealed that the specific surface area (SSA) and total pore volume of the PG reached to 358 m2/g and 0.370 cm3/g, respectively. The adsorption capacity of methylene blue (MB) for the glasses was measured in the dark, instead the photocatalytic MB removal efficiency was evaluated by the degradation of MB under UV light illumination using a UV–vis spectrometer. The MB removal efficiency of the TiO2 synthesized anatase powder was only 32.3 % whereas, for TiO2 embedded PG (TiPG) it was 91.6 %, and nearly complete (> 99 %) efficacy was achieved for TiO2 embedded alkaline leached PG (TiPG-AL) under UV illumination 3 h period. Better MB removal efficiency was attributed to high SSA and dispersion of nano size anatase TiO2 crystallites within the porous structure. © 2020 Elsevier LtdArticle Citation - WoS: 40Citation - Scopus: 44Plasmon-Enhanced Photocatalytic and Antibacterial Activity of Gold Nanoparticles-Decorated Hematite Nanostructures(Elsevier Ltd., 2021) Emre, Alp; İmamoğlu, Rizvan; Savacı, Umut; Turan, Servet; Kazmalı, M. Kürşat; Genç, AzizHematite (alpha-Fe2O3) nanoparticles have received significant attention from the researchers due to their favorable and desirable properties in diverse applications. In the present study, single-crystalline hematite pseudo-nanocubes and porous nanorods were synthesized by the hydrothermal route without the usage of any surfactant agents, which were then decorated with gold nanoparticles hidrothermally in an aqueous solution in order to increase the solar energy conversion efficiency. The photocatalytic activities of synthesized nanoparticles were studied against Rhodamine B (RhB) under the illumination of AM 1.5 solar simulator. The excellent photocatalytic efficiency was obtained by changing morphological features of hematite nanostructures, along with the photocatalytic performance enhancement up to 25% thanks to the surface plasmon resonances for the gold nanoparticles-decorated hematite nanostructures. For instance, gold-nanoparticles decorated hematite pseudo-nanocubes almost completely degraded all the RhB after 30 min of illumination. It was also observed that all hematite products, with and without gold decoration, exhibited an impressive antibacterial effect and showed the lethal effect in E.coli. The same nanoparticles being photocatalytically active for organic pollutant degradation and having antibacterial effect may have a good potential for waste water remediation applications. (C) 2020 Elsevier B.V. All rights reserved.Article Citation - WoS: 31Citation - Scopus: 33Enhanced Bactericidal and Photocatalytic Activities of Zno Nanostructures by Changing the Cooling Route(Royal Society of Chemistry, 2018) Horzum, Nesrin; Hilal, Mohamed Elhousseini; Işık, TuğbaWe report on a simple synthesis of ZnO nanowires by calcination of zinc acetate. The effect of calcination temperature and cooling route on the antibacterial and photocatalytic properties is demonstrated by varying the size and surface area of the nanowires. The decrease of the calcination temperature followed by a rapid cooling procedure leads to a smaller size and larger surface area of the nanowires. ZnO nanowires are found to be effective against the growth of E. coli at the microgram level. In addition, the photocatalytic activity of the synthesized ZnO nanowires is demonstrated by the successful degradation of the organic dye methylene blue.