Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Access Right: Open AccessAuthor: search.filters.author.Büyükçakır, Onur

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Now showing 1 - 4 of 4
  • Master Thesis
    Utilization of Graphene and Mos2 for Volatile Organic Compound Sensor Applications
    (01. Izmir Institute of Technology, 2023) Şahin, Hasan; Büyükçakır, Onur; Büyükçakır, Onur; Şahin, Hasan; 04.04. Department of Photonics; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    The 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; Şahin, Hasan; Büyükçakır, Onur; Büyükçakır, Onur; Şahin, Hasan; 04.04. Department of Photonics; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    The 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
    Design and Synthesis of Anthracenetetrone-Based Redox-Active Porousorganic Polymer as a Cathode Material for Zinc-Ion Batteries
    (01. Izmir Institute of Technology, 2023) Büyükçakır, Onur; Büyükçakır, Onur; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    Aqueous 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
    Synthesis of Indandione-Based Porous Organic Polymers and Their Applications in Zinc-Ion Batteries
    (01. Izmir Institute of Technology, 2022) Büyükçakır, Onur; Büyükçakır, Onur; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    There 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.