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.Review Citation - WoS: 10Citation - Scopus: 14A Review on Characterization and Recyclability of Pharmaceutical Blisters(Elsevier, 2023) Capkin, Irem Yaren; Gokelma, MertolPackaging is one of the biggest sectors in the world and the use of aluminium is widespread in the packaging industry. Pharmaceutical blister packages generate a significant amount of solid waste, typically containing plastics and aluminium as thin layers. Since these packages have a complex structure with multiple layers, they are hard to recycle. A separation process of the plastic and aluminium is needed prior to recycling. Hydrometallurgical or thermal processes can be used for the separation. This work reviews the characterization of different types of blisters and the different reagents used in the separation process of the blister layers. Parameters and results of separation processes by using hydrochloric acid, formic acid, acetic acid, organic solvents, and phosphoric acid were discussed as well as the thermal degradation.Article Citation - WoS: 9Citation - Scopus: 9Cold Sintering Assisted Two-Step Sintering of Potassium Sodium Niobate (knn) Ceramics(Elsevier, 2023) Karacasulu, Levent; Ahmetoğlu, Çekdar VakıfPotassium sodium niobate (KNN) ceramics were densified using a multiple-stage sintering process in which initially applied cold sintering process (CSP) was followed by the solid-state sintering between 1100 and 1120 °C. Comparative assessments demonstrated that multi-step sintered samples yielded better properties than conventionally sintering ones. The highest relative density (94.7%) and the best electrical properties were obtained from the sample subjected to cold sintering at 120 °C/1 h using 5 wt% deionized water subsequently heat-treated at 1120 °C/2 h, resulting in a monolithic KNN ceramic having a piezoelectric coefficient of 120 pC/N. © 2023 Elsevier B.V.Article Citation - WoS: 20Citation - Scopus: 22Fabrication and Properties of Novel Porous Ceramic Membrane Supports From the (sig) Diatomite and Alumina Mixtures(Elsevier, 2022) Aouadja, Faycal; Bouzerara, Ferhat; Güvenç, Çetin Meriç; Demir, Mustafa M.In this paper, the manufacturing of macro-porous tubular ceramic supports for membranes is described. The novel supports are fabricated from natural diatomite and alumina raw materials using the extrusion method. The structure was analyzed by X-ray diffraction (XRD) and mercury porosimetry techniques; the presence of possible defects was investigated by scanning electron microscopy (SEM). The permeability has been measured from water flux in standard experiments. Experimental results show that the open porosity, the average pore size (APS), the pore size distribution, the strength, and the permeability of sintered supports, have been found to depend, mainly on the concentration of alumina (Al2O3) additive. Supports prepared with the addition of 10 wt.% of alumina and sintered at 1200 degrees C, can be considered as the most optimized; they have a porosity ratio of about 46%, an APS is around 7.7 mu m, a flexural strength value of about 28 MPa, and water permeability of around 15 m(3)h(-1) m(-2) bar(-1). Such materials could be of great interest in the supports fabrication for membrane application, for instance, water filtration. (C) 2021 SECV. Published by Elsevier Espana, S.L.U.Article Citation - WoS: 28Citation - Scopus: 33Cold Sintering as a Promising Isru Technique: a Case Study of Mars Regolith Simulant(Elsevier, 2023) Karacasulu, Levent; Karl, David; Gurlo, Aleksander; Ahmetoğlu, Çekdar VakıfMars regolith simulant (MGS-1) was densified for the first time via a cold sintering process (CSP) as a novel in-situ resource utilization (ISRU) concept. The technique comprises the utilization of NaOH solution as a liquid media during the densification of simulant powder with <100 μm particle size. In as short as 30 min, with the increase in the NaOH concentration (from 3 M to 10 M) and processing temperature (from 150 °C to 250 °C), the relative densities of the regolith compacts and the mechanical properties were enhanced. The artifacts produced with Mars regolith simulant powder at 250 °C using 10 M NaOH solution yielded a relative density of around 88% and compressive strength reaching ∼45 MPa.Article Citation - WoS: 3Citation - Scopus: 6Hybrid Photonic-Plasmonic Mode-Coupling Induced Enhancement of the Spontaneous Emission Rate of Cds/Cdse Quantum Emitters(Elsevier, 2022) Gökbulut, Belkıs; İnanç, Arda; Topçu, Gökhan; Özçelik, Serdar; Demir, Mustafa Muammern this paper, a hybrid photonic-plasmonic resonator, which comprises an electrospun polymer fiber with a micrometer diameter and a core/shell nanostructure with a gold nanoparticle core, is constructed to investigate the dynamics of the coupled spontaneous emission of CdS/CdSe quantum dots (QDs). The gold nanoparticle core; covered with a silica shell, anchored with individual CdS/CdSe QDs, is placed inside a hollow cylindrical nanocavity formed on the surface of the microfiber to enable integration of the optical mode with the plasmonic effect, which is induced by the localized surface plasmons of the metal nanoparticle being present in the vicinity of the dipoles. The spontaneous emission rate of the QDs, coupled into the hybrid photonic-plasmonic mode, is measured to enhance by a factor of 23 via a time-resolved experimental technique. This result suggests that the regeneration of the optical mode-field inside the photonic-plasmonic resonator through the interaction of the dipoles with the localized surface plasmons of a metal nanoparticle strongly enhances the density of the electromagnetic states of the quantum emitters to facilitate an enhanced spontaneous emission within the host medium of the proposed polymer based-photonic structure.Article Citation - WoS: 10Citation - Scopus: 12The Effect of Dopa Hydroxyl Groups on Wet Adhesion To Polystyrene Surface: an Experimental and Theoretical Study(Elsevier, 2020) Yıldız, Remziye; Özen, Sercan; Şahin, Hasan; Akdoğan, YaşarMussels wet adhesive performance has been arousing curiosity for a long time. It is found that 3,4-dihydroxyphenylalanine (DOPA) is responsible for adhesive properties of mussels. Despite a large body of research characterizing the interactions DOPA with hydrophilic surfaces, relatively few works have addressed the mechanism of interactions with hydrophobic surfaces. The benzene ring of DOPA is the main attributor to the adhesion on hydrophobic polystyrene (PS) surface. However, here we showed that two hydroxyl groups of catechol have also effects on wet adhesion. We studied wet adhesive properties of DOPA, tyrosine and phenylalanine functionalized PEG polymers, PEG-(N-Boc-L-DOPA)(4), PEG-(N-Boc-L-Tyrosine)(4), PEG-(N-Boc-L-Phenylalanine)(4), on spin labeled PS nanobeads (SL-PS) by electron paramagnetic resonance (EPR) spectroscopy. Surface coverage ratio of SL-PS upon additions of PEG-(N-Boc-L-DOPA)(4), PEG-(N-Boc-L-Tyrosine)(4) and PEG-(N-Boc-L-Phenylalanine)(4) showed that SL-PS was covered with 70%, 50% and 0%, respectively. This showed that spontaneous wet adhesion on PS increases with the number of amino acids hydroxyl groups. This is also supported with the density functional theory (DFT) energy calculations and ab-initio molecular dynamics (AIMD) simulations. In water, interactions between water molecules and hydroxyl groups on the catechol induce catechol adhesion via 7C-7C stacking between the catechol and double styrene rings which were already tilted out with water.Article Citation - WoS: 13Citation - Scopus: 12Orthorhombic Cspbi3 Perovskites: Thickness-Dependent Structural, Optical and Vibrational Properties(Elsevier, 2020) Özen, Sercan; İyikanat, Fadıl; Özcan, Mehmet; Tekneci, Gülsüm Efsun; Eren, İsmail; Sözen, Yiğit; Şahin, HasanCesium lead halide perovskites have been subject to intense investigation, mostly because of their potential to be used in optoelectronic device applications. However, regarding the need for nanoscale materials in forthcoming nanotechnology applications, understanding of how the characteristic properties of these perovskite crystals are modified through dimensional crossover is essential. In this study, thickness-dependence of the structural, electronic and vibrational properties of orthorhombic CsPbI3, which is one of the most stable phase at room temperature, is investigated by means of state-of-the-art first-principles calculations. Our results show that (i) bilayers and monolayers of CsPbI3 can be stabilized in orthorhombic crystal symmetry, (ii) among; the possible ultra-thin perovskites only structures with CsI-terminated surface are dynamically stable (iii) electronic band gap increases with decrease in perovskite thickness due to quantum size effect and (iv) reflectivity and transmissivity of the orthorhombic CsPbI3 can be tuned by varying the thickness that modifies the electron confinement. (c) 2019 Elsevier B.V. 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