Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Synthesis and Investigation of Quinone-Pyrrole Polymeric Materials for Zinc-Ion Batteries(01. Izmir Institute of Technology, 2024) Çanakçı, Utku Cem; Büyükçakır, OnurFosil yakıtların günümüzde yaygın kullanımı çevre üzerinde yıkıcı bir etkiye sahiptir. Bu durum, çevre dostu alternatif enerji kaynaklarının benimsenmesini zorunlu kılmıştır. Çinko-iyon piller, bu bağlamda önemli potansiyele sahip, gelişmekte olan yeni bir enerji depolama sistemi sınıfını temsil etmektedir. Bununla birlikte, bu teknolojiyi ilerletmekteki büyük zorluk, Zn2+ iyonlarını verimli ve geri dönüşümlü olarak barındırabilen katot malzemeleri geliştirmektir. Kinon bazlı konjuge polimerik malzemeler, redoks aktif yapıları, kolayca değiştirilebilen yapıları ve güçlü kimyasal ve termal kararlılıkları nedeniyle çinko-iyon pilleri için mükemmel katot seçenekleridir. Bu çalışmada, çinko-iyon pilleri (ÇİP'ler) için katot malzemeleri olarak kinon-pirol konjuge polimerik malzemeler (QRP'ler) sentezlendi. QRP'lerin içsel özellikleri, redoks merkezlerine etkili Zn2+ difüzyonunu kolaylaştırarak uzun vadeli döngü kararlılığını sağlar. QRP-1 ve QRP-2 sırasıyla 0.1 mA g-1 akım yoğunluğunda 180 mA h g-1 ve 134 mA h g-1 deşarj kapasitesi gösterdi. QRP'ler, 2.0 A g-1 akım yoğunluğunda 10000 döngü boyunca olağanüstü döngü kararlılığı göstererek, QRP-1 ve QRP-2 için sırasıyla 42 mA h g-1 ve 104 mA h g-1 olmak üzere oldukça yüksek final kapasiteleri elde edildi. Bu çalışmanın, kinon bazlı konjuge polimerik malzemelerin çinko-iyon piller için etkili katot malzemeleri olarak potansiyelini gösterdiğine ve enerji depolama alanında çalışan araştırmacılarının dikkatini çekeceğine inanıyoruz.Master Thesis Synthesis and Characterization of Polycaprolactone-Polyvalerolactone Copolymer and Its Use in Melt Electrowriting Applications(01. Izmir Institute of Technology, 2024) Dinçkal, Sanem; Yıldız, Ümit HakanThis thesis focuses on the synthesis and characterization of Poly(ε-caprolactone) (PCL) and its block copolymers, Poly(ε-caprolactone)-b-Poly(4-hydroxyvalerate) (PCL-b-P4HV) and Poly(ε-caprolactone)-b-Poly(δ-valerolactone) (PCL-b-PVL). These polymers were synthesized through ring-opening polymerization of various lactones (ε-caprolactone, γ-valerolactone, and δ-valerolactone) using biocatalysts such as citric acid, glycolic acid, salicylic acid, boric acid and acetic acid. Detailed analytical and thermoanalytical characterizations were performed. Differential Scanning Calorimetry (DSC) showed that most homopolymers and copolymers exhibited crystallization (Tc) and melting temperatures (Tm) varying between 5-25°C and 50-65°C respectively, confirming successful polymerization. DSC thermograms of block copolymers revealed that solvent choice for precipitation affected crystallinity and thermal properties, with a small second melting point observed due to different crystalline forms. Fourier Transform Infrared Spectroscopy-Attenuated Total Reflectance (FTIR-ATR) confirmed the homopolymerization of Poly(ε-caprolactone) using citric, glycolic, and salicylic acids. Mass spectrometry further revealed characteristic peaks corresponding to expected molecular weights and compositions of the copolymers. The presence of these peaks corroborated the formation of block copolymers with distinct blocks of PCL, P4HV, and PVL confirmed the molecular integrity of the synthesized block copolymers. This thesis provides a comprehensive analysis of the synthesis and characterization of block copolymers, offering insights into their structural properties and potential applications. The findings contribute to the understanding of the polymerization process and the properties of the resulting materials, which are significant for industrial and biomedical applications. The resultant copolymers were utilized in Melt Electrowriting process to provide tissue scaffold. Despite their brittleness, all copolymers were electrowritten without issues, indicating their potential interest in tissue engineering applications.Master Thesis Exploring the Electronic and Magnetic Characteristics of Lithiated Holey Mo8s12: a Study in Inorganic Chemistry(2023) Tan, Fırat; Büyükçakır, Onur; Şahin, HasanSince graphene, the ultra-thin carbon compound, gained popularity with its remarkable electrical capabilities, various two-dimensional (2D) van der Waals-type materials have come into focus. Investigation of the electrical and optical properties of materials at atomic scale is required to understand the unique electronic behavior brought on by quantum size effects. The development of optoelectronic devices with novel features is facilitated by an increased understanding of the properties of matter within the context of theoretical techniques. This thesis includes the investigation of the lithiated holey Mo8S12 structure through calculations based on density functional theory (DFT). Motivated by the recent experimental realization of holey structure of transition metal dichalcogenides (TMDs), in this thesis, the holey structure of Mo8S12 is investigated by means of DFT-based calculations. The geometry optimization and phonon band dispersion calculations show the structural and dynamical stability of free-standing holey single-layer Mo8S12. In addition, electronic band dispersions reveal the direct band gap semiconducting nature of the structure. In order to investigate the lithiation capacity of single-layer Mo8S12, effect of Li doping on the properties of Mo8S12 is analyzed by considering both one- and double-sided lithiation. As one surface of single-layer Mo8S12 is fully saturated with Li atoms, a dynamically stable half-metallic structure is formed. The corresponding electronic band structures reveals the metallic behavior of the two-side lithiated single-layer. Overall, tunable electronic properties of single-layer holey Mo8S12 via lithiation makes it suitable candidate for various nanoelectronic applications, such as memories, capacitors, gate insulators, energy storage, high-frequency modulation in communication devices.Master Thesis Utilization of Graphene and Mos2 for Volatile Organic Compound Sensor Applications(01. Izmir Institute of Technology, 2023) Duran, Tuna; Büyükçakır, Onur; Şahin, HasanThe novel 2D materials such as graphene and transition-metal dichalcogenides have already shown impressive volatile organic compound (VOC) gas monitoring performances as in sensitivity, limit of detection and response time. This thesis discusses the experimental-theoretical examination of optical, electronic and morphological properties of novel 2D materials and their utilization in VOC gas sensor field, by means of several characterization techniques and density functional theory (DFT). Aside from the basic familiarization with the experimental and theoretical methodology in Chapter 2, examination of the functionalization of exfoliated MoS2 using DDT (1-Dodecanethiol) in Chapter 3, which eventually led to a research paper. The DDT treatment is incorporated into the NMP (N-methyl pyrrolidone) exfoliation procedure, resulting in successful functionalization as confirmed by optical, morphological, and theoretical analysis. Raman spectroscopy showed the formation of graphitic species on MoS2 sheets, with decreased sulfur-vacant sites as the DDT ratio increased. STEM and AFM data confirmed the presence of graphitic quantum dots (GQDs) on MoS2 nanosheets, while PL intensities demonstrated significant improvements in photoluminescent properties. This study enhances our understanding of surface and edge chemistry in exfoliated MoS2 and expands the possibilities for broader applications of MoS2 and GQD particles. Moreover, the attention was drawn to the investigation of the contrasting responses of graphene gas sensors fabricated using different synthesis methods, in the submitted paper explained in Chapter 4. Exfoliated graphene sensors decrease in current when exposed to methanol, while CVD graphene sensors increase in current. The differences in edge site population and electrical properties contribute to these responses. The study provided theoretical and experimental findings for an understanding of the reasons behind the inverse sensor responses of CVD and exfoliated graphene on an atomic scale.Master Thesis Investigation of Electronic, Vibrational, Mechanic and Chemicalproperties of 2d-Dlhc Cui Crystal(01. Izmir Institute of Technology, 2023) Demirok, Ali Cem; Büyükçakır, Onur; Şahin, HasanThe branch of material science and nanotechnology has recently seen the emergence of a remarkable class of materials known as 2D materials. These materials have unusual features and behaviours because of their special two-dimensional structure that separates them apart from bulk materials. One of the characteristics of 2D materials are related to their capacity to handle large mechanical deformation without fracture. Since the discovery of graphene, researchers have discovered and created an extensive range of additional 2D materials with a variety of chemical compositions and topologies. These materials can be used for energy storage, sensing, catalysis and biomedical applications. In this thesis, electronic, vibrational, mechanic and chemical properties of singlelayer CuI were investigated by using density functional theory (DFT) based first-principles calculations. It is shown that the CuI structure crystallizes in a hexagonal lattice by energy and geometry optimizations. The vibrational properties of the material were examined by phonon and Raman calculations and the structure found to be dynamically stable and there were four Raman active modes. The electronic band dispersions and corresponding density of states showed that the single-layer CuI crystal has semiconductor nature with direct band gap. Strain calculations were performed to examine the mechanical strength of the CuI crystal. Effect of biaxial strain on the electronic band structure of CuI crystal was investigated in the range of 5% and the direct band gap behaviour did not change. Biaxial and uniaxial strain calculations have shown that it is resistant to high stresses.Master Thesis Lyotropic Liquid Crystal Templated Synthesis of Single-Crystalline Gold Microplates and Transparent Conductive Reduced Graphene Oxide Thin Films(01. Izmir Institute of Technology, 2023) Akkuş, Betül; Mert Balcı, FadimeSurfactants organize to form various mesophases of lyotropic liquid crystal (LLC) in the presence of water. In the literature, some acids, salts, and ionic liquids have also been used to form ordered LLC mesophases. In this thesis, two dimensional (2D) single-crystalline gold (Au) nano- and microplates and reduced graphene oxide (RGO) thin films have been synthesized using LLC mesophases. Stable LLC mesophases have been formed using 10-lauryl ether (C12EO10), an oligo-type surfactant, and sulfuric acid (H2SO4), a strong acid. Au plates with various anisotropic structures, such as triangular, truncated triangular, hexagonal, and gear-like, have been synthesized by a photochemical method in the presence of LLC mesophase. Most importantly, Au plates up to 39 µm in width have been obtained in the confined space of the LLC medium. The thickness of the obtained Au plates varies from 50 nm to 150 nm. The size and/or morphology of Au products synthesized in LLC medium depends on the power of the light source, the irradiation time, the amount of Au precursor added, the addition of different capping agents, and various inorganic salts. Additionally, spin-coated RGO thin films have been synthesized using the LLC mesophase for use as a transparent and conductive electrode in various electrochemical devices. The LLC mesophase has improved the sheet resistance values of RGO thin films. RGO thin films with a sheet resistance of 31 kΩ/sq and an optical transmittance of 92% at 550 nm have been achieved at the high thermal annealing temperature under an inert atmosphere.Master Thesis Design and Synthesis of Anthracenetetrone-Based Redox-Active Porousorganic Polymer as a Cathode Material for Zinc-Ion Batteries(01. Izmir Institute of Technology, 2023) Begar, Ferit; Büyükçakır, OnurAqueous zinc ion batteries (AZIBs) are a new class of energy storage devices with significant potential for large-scale applications. However, developing suitable cathode materials that can efficiently and reversibly accommodate Zn2+ ions remains a key obstacle in advancing this technology. Porous organic polymers (POPs) are materials characterized by their interconnected network of pores at the molecular level. These versatile polymers exhibit unique properties such as high surface area, tunable porosity, and diverse functionality. POPs hold great potential for various technological advancements, and recently, they have attracted significant interest in energy storage applications due to their exceptional physical and chemical properties, which endow structural durability and electrochemical superiority. In this study, we reported the synthesis of a new redox-active quinone-rich porous organic polymer (rPOP) as a cathode material for AZIBs. The highly porous nature of rPOP enables successful Zn2+ diffusion into the redox centers. The structural durability of the polymeric materials provides ultra-long cycle life. The cell containing rPOP cathode delivered a discharge capacity of 120 mA h g-1 at a current density of 0.1 mA g1 . Most importantly, the rPOP revealed extraordinary cycling stability at 1.0 A g-1 for 10000 charge/discharge cycles and at 2.0 A g-1 for 30000 charge/discharge cycles with capacity retentions of %95 and %66, respectively. The detailed investigation of the charge storage behavior of rPOP cathode, using ex/in-situ analysis, revealed that H+ acts as a secondary charge carrier along with the Zn2+, contributing to 17% of the overall capacity. This study demonstrates the effective utilization of POPs as a cathode material for AZIBs, and we believe that it will attract the attention of researchers in the energy storage field.Master Thesis Borylation of Petroleum Cracking Olefin Products(01. Izmir Institute of Technology, 2022) Arapoğlu, Mehmet Anıl; Artok, LeventCracking is a process that long-chain hydrocarbons are broken down into more valuable fragments called naphtha cracking products. The olefins formed as a result of this process have various functions such as forming the smallest building blocks of fine and speciality chemicals. It has been foreseen that borylation processes can be applied as a conversion method of these products into valuable intermediate structures. In this context, this thesis describes first time the transition-metal-catalyzed borylation of a number of petroleum cracking olefin products. Borylation reactions have been extensively investigated in the literature and have become one of the popular methods for synthesizing organoboron reagents, which can also be used in the synthesis of functional materials, pharmaceuticals, and agricultural chemicals. In the context of this thesis, petroleum cracking olefinic products were converted into high-value-added organoboron derivatives by metal-catalysed hydroboration and dehydrogenative borylation methods. For this purpose, the experimental conditions were optimized using propene and isobutene reagents. It has been shown in this study that iridium complexes with N-Heterocarbene (NHC) ligands are highly effective catalysts and therefore anti-Markovnikov hydroboration products can be produced in excellent yields even at very low catalyst loadings. On the other hand, alkenyl boron products could be obtained with high yields, which could be performed in the absence of dehydrogenative borylation reactions, ligand, base, and any other additives. The applicability of these methods in internal and terminal alkenes such as cyclohexene, ethene, decene and styrene has been also demonstrated. Finally, these products were converted into a number of intermediates by Suzuki-Miyaura cross-coupling reactions. Thus, in the conversion of alkenes to valuable intermediates, practical and sustainable applications would be possible by using simple, abundant, and cheap reagents instead of expensive and dangerous chemicals.Master Thesis Investigation of Ion Transport Properties of Organic Electrochemical Transistors(01. Izmir Institute of Technology, 2022) Küçüktartar, Tuğçe; Yıldız, Ümit HakanOrganic electrochemical transistors (OECTs) comprise large amplification in current response while operating at low voltages and have high transconductance due to its volumetric capacitance created by ion injection from electrolyte through the whole organic semiconductor channel. OECTs are switchable by doping and de-doping of active channel via application of positive or negative gate bias. One of the most common organic material for OECTs is the conductive polymer, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). PEDOT:PSS offers prominent advances because of their coupled electronic and ionic conductance, morphology and optical properties. Although the complex working principle of OECT has been tried to be elaborated with several models in literature, the conduction of ions and electrons in the channel has not been fully elucidated. In this thesis, the transformations between un-doped, doped and de-doped state investigated systematically based on the electrical (OECT), structural and morphological characterization of PEDOT:PSS thin film. Measurements were conducted with different dopant molecules and the repeatability of the device was investigated. As a result, the most stable drain and gate voltage range in which the device works has been determined. In addition, the X-ray photoelectron spectroscopy (XPS) investigation performed which is revealed that the density of the bipolaron formation of PEDOT:PSS in the doped state increase as compared to its natural form in the de-doped state. XPS mapping on OECT devices suggested that ions migration is homogeneously generated by applied bias.Master Thesis Synthesis of Indandione-Based Porous Organic Polymers and Their Applications in Zinc-Ion Batteries(01. Izmir Institute of Technology, 2022) Şimşek, Gizem; Büyükçakır, OnurThere has been growing interest in porous organic polymers (POPs) in recent years due to their large surface area, easy chemical tunability, sustainability, and high thermal and chemical stability. Due to their exceptional properties, they are suitable for use as platforms in various applications, including gas storage, separation, catalysis, and, more recently, energy storage systems. In this regard, it is imperative to design new functional POPs with a large surface area, permanent porosity, and physicochemical stability. In this thesis, we have presented indandione-based POPs (r-POPs) prepared by an acid-catalyzed condensation reaction between s-indacene-1,3,5,7(2H,6H)-tetraone and benzene-1,3,5-tricarboxaldehyde under highly environmentally friendly conditions. In order to optimize the reaction conditions, we first synthesized the model compound, namely 2-benzylidene-1H-indene-1,3(2H)-dione. The model compound was characterized by using 1H and 13C-NMR spectroscopy. Using different types of acids, we have investigated the effect of acid on polymerization and its textural properties. The polymers were characterized using various characterization techniques. Due to increased interest in renewable energy as a fossil fuel substitute, energy storage systems have attracted colossal interest, and rechargeable aqueous zinc-ion batteries (ZIBs) are seen as promising energy storage systems, particularly for grid-scale applications. In this respect, the carbonyl-rich structure of r-POPs transforms them into a potential electrode material. Thus, we have also investigated their electrochemical performances as cathode materials for ZIBs. Although r-POPs showed low electrochemical performance in capacity and cycle life, they have great potential to be an electrode material in other metal-ion batteries.