Cihanoğlu, Gizem
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Cihanoglu, G.
G. Cihanoglu
G. Cihanoglu
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01. Izmir Institute of Technology
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Former Staff
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Sustainable Development Goals
1NO POVERTY
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2ZERO HUNGER
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3GOOD HEALTH AND WELL-BEING
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4QUALITY EDUCATION
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5GENDER EQUALITY
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6CLEAN WATER AND SANITATION
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7AFFORDABLE AND CLEAN ENERGY
2
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8DECENT WORK AND ECONOMIC GROWTH
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9INDUSTRY, INNOVATION AND INFRASTRUCTURE
3
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10REDUCED INEQUALITIES
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11SUSTAINABLE CITIES AND COMMUNITIES
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12RESPONSIBLE CONSUMPTION AND PRODUCTION
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13CLIMATE ACTION
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14LIFE BELOW WATER
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15LIFE ON LAND
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16PEACE, JUSTICE AND STRONG INSTITUTIONS
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17PARTNERSHIPS FOR THE GOALS
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Scholarly Output
6
Articles
5
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28446/1721
Supervised MSc Theses
0
Supervised PhD Theses
1
WoS Citation Count
30
Scopus Citation Count
38
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0
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0
WoS Citations per Publication
5.00
Scopus Citations per Publication
6.33
Open Access Source
4
Supervised Theses
1
| Journal | Count |
|---|---|
| Industrial & Engineering Chemistry Research | 1 |
| International Journal of Energy Studies (Online) | 1 |
| Journal of Materials Science | 1 |
| Journal of the Turkish Chemical Society, Section A: Chemistry | 1 |
| Polymers | 1 |
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6 results
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Now showing 1 - 6 of 6
Article Citation - WoS: 9Citation - Scopus: 10Cvd Deposited Epoxy Copolymers as Protective Coatings for Optical Surfaces(MDPI, 2023) Karabıyık, Merve; Cihanoğlu, Gizem; Ebil, ÖzgençCopolymer thin films of glycidyl methacrylate (GMA), ethylene glycol dimethacrylate (EGDMA) and 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4D4) were synthesized via initiated chemical vapor deposition (iCVD) as protective coatings for optical surfaces. Chemical durability in various solvents, corrosion resistance, adhesion to substrate, thermal resistance and optical transmittance of the films were evaluated. Crosslinked thin films exhibited high chemical resistance to strong organic solvents and excellent adhesion to substrates. Poly(GMA-co-EGDMA) and poly(GMA-co-V4D4) copolymers demonstrated protection against water (<1% thickness loss), high salt resistance (<1.5% thickness loss), and high optical transparency (~90% in visible spectrum) making them ideal coating materials for optical surfaces. Combining increased mechanical properties of GMA and chemical durability V4D4, the iCVD process provides a fast and low-cost alternative for the fabrication of protective coatings.Article Citation - WoS: 8Citation - Scopus: 7Cvd-Deposited Oxygen-Selective Fluorinated Siloxane Copolymers as Gas Diffusion Layers(American Chemical Society, 2022) Cihanoğlu, Gizem; Ebil, ÖzgençCopolymer thin films of 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4D4), 2-(perfluorohexylethylacrylate) (PFHEA), and 2-(perfluoroalkylethylmethacrylate) (PFEMA) were synthesized via initiated chemical vapor deposition (iCVD) as potential candidates for gas diffusion layers (GDLs) in gas diffusion electrodes (GDEs) for aqueous metal–air batteries. Thin-film GDLs exhibited an average water vapor transmission rate of 7.5 g m–2 day–1 and enhanced oxygen diffusion with oxygen permeabilities as high as 3.53 × 10–15 mol m m–2 s–1 Pa–1 (10.5 Barrer). The electrochemical performance of GDEs fabricated using commercial catalysts, current collectors, and synthesized GDLs was investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and potentiodynamic polarization measurements. The fabricated GDEs exhibited higher oxygen reduction current densities (228.2 mA cm–2) compared to commercial GDEs (132.7 mA cm–2). Copolymer GLDs exhibited an order of magnitude higher oxygen diffusion (39.5 × 10–8 cm2 s–1) in GDEs compared to commercial counterparts (1.84 × 10–8 cm2 s–1). Due to the high oxygen solubility of V4D4 and excellent hydrophobic behavior of PFHEA and PFEMA, their copolymers can effectively promote the diffusion of oxygen and restrict moisture intake, making them ideal materials for GDLs. Combining well-balanced properties of siloxane and fluorinated polymer chemistries, the iCVD process is an excellent low-cost method for the fabrication of GDLs for metal–air battery applications.Article Fabrication and Characterization of Ni-based Electrodes for Improved NiZn Battery Performance(2025) Cihanoğlu, GizemBu çalışmada, nikel-çinko (NiZn) bataryasında nikel elektrot olarak kullanılmak üzere aktif malzeme olan nikel hidroksit (Ni(OH)2) tozlarını sentezlemek için hidrotermal yöntem kullanılmıştır. Hazırlanan Ni elektrotlardaki katot malzemesini karakterize etmek için X-ışını kırınımı (XRD), taramalı elektron mikroskobu (SEM), zeta potansiyeli, Brunauer-Emmett-Teller (BET) ve elektrokimyasal performans testleri kullanılmıştır. Sonuçlar, kristal yapıya sahip β-fazlı nano boyutta küresel Ni(OH)2 partiküllerin sentezlendiğini göstermiştir. Elektrokimyasal test sonuçları ise Ni elektrodun yarı hücrede kararlı bir çevrim döngüsüne sahip olduğunu göstermiştir. Elektrokimyasal performans sonuçlarına göre, sentez sıcaklığı 70oC olan ve sentez sonrası 3 saat boyunca bekletildikten sonra elde edilen Ni(OH)2 tozları ile hazırlanan Ni elektrot (Ni_pH12_3h_70oC) en iyi performans gösteren metal hidroksit olmuştur. Nikel elektrotlar birbiriyle karşılaştırıldığında, NiCoZn elektrot yüksek OER (oksijen evrim reaksiyonu) ve ORR (oksijen indirgeme reaksiyonu) aktiviteleri sergilemiştir, çünkü kobalt ve çinko oksitlerin nikel ile kombinasyonu mükemmel elektrolit erişim kabiliyeti ve aktif malzeme boyunca etkili iyon transferi sağlamaktadır. NiZn batarya içerisinde kullanılan NiCoZn elektrotu 10 mA cm-2 akım yoğunluğunda 192,7 mAh gaktif-1 değere ulaşarak yüksek bir kapasite ve kararlı bir çevrim döngüsü (10 mA cm-2'de 70 çevrim döngüsü sonucunda) sergilemiştir. NiCoZn elektrodu Ni, Co ve Zn arasındaki mükemmel etkileşmi ile, yüksek başlangıç potansiyeli ve akım yoğunluğu sergilemiş; bu da NiCoZn elektrotun NiZn bataryalardaki Ni-tabanlı elektrotlar için yüksek performanslı bir konfigürasyon olarak umut verici bir aday olduğunu göstermiştir.Doctoral Thesis Electrochemical and Oxygen/Water Permeation Behavior of Fluorinated Siloxane Copolymers Synthesized Via Initiated Chemical Vapor Deposition(Izmir Institute of Technology, 2021) Cihanoğlu, Gizem; Ebil, ÖzgençMetal-air batteries are considered as one of the best alternatives to current Li-ion batteries with their high energy densities (1000-13000 Wh/kg) also, they are lightweight, cheap, and safe. However, secondary alkaline metal-air batteries suffer from catalyst corrosion, anode passivation and corrosion, electrolyte loss, and pore-clogging leading to performance loss and reduced cycle life. This thesis aims to evaluate the feasibility of highly cross-linked, hydrophobic, and oxygen selective thin homopolymers and copolymers films as potential candidates for Gas Diffusion Layer (GDL) materials in Gas Diffusion Electrodes (GDEs) for alkaline metal-air batteries. Homopolymers of 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4D4), 2-(perfluorohexyl)ethyl acrylate (PFHEA) and 2-(perfluoroalkyl)ethylmethacrylate (PFEMA) and their copolymers were synthesized via initiated chemical vapor deposition (iCVD). iCVD deposited fluoropolymer thin films exhibited low water transmission rates and excellent oxygen diffusion with a high oxygen/water selectivity up to 13.6. GDEs with iCVD GDLs exhibited higher oxygen reduction current density (228.2 mA cm-2) when compared to commercial counterparts (132.7 mA cm-2). In addition, the chemical stability, durability and corrosion protection aspects of these films were investigated by substrate adhesion and immersion tests in organic solvents and NaCl solution. The results of the corrosion test together with chemical stability and durability evaluation indicate that iCVD deposited copolymers exhibit excellent adhesion, good solvent resistance and offer effective physical and chemical protection without the need for surface pretreatment. iCVD copolymer films provide better anti-corrosion barriers with lower corrosion efficiency (85-99 %) for metal surfaces compared to homopolymer counterparts. By combining siloxane and fluorinated matrix, the copolymer films provide enhanced oxygen transport and reduce moisture entrance significantly as a GDLs and also improve physical, chemical, corrosion protection.Article Citation - Scopus: 7Binder Effect on Electrochemical Performance of Zinc Electrodes for Nickel-Zinc Batteries(Turkish Chemical Society, 2018) Ebil, Özgenç; Cihanoğlu, GizemPolyethylene glycol (PEG) and polyvinyl alcohol (PVA) were used as a zinc electrode binder at different concentrations to enhance the electrochemical behavior of zinc electrodes for nickel-zinc (NiZn) batteries. ZnO powders synthesized by mechanochemical and hydrothermal precipitation methods were mixed with lead oxide, calcium hydroxide and binder to prepare zinc electrodes in pouch cell NiZn batteries. Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) analysis reveal that initial morphology of zinc electrode changes drastically regardless of the binder type and its loading after charge/discharge process, and even the charge/discharge process is not complete. The results show that the presence of PEG causes better discharge capacity compared to that of PVA as a binder. Zinc electrode prepared using commercial ZnO powder and 3 wt.% PEG gives the optimum discharge capability, with a specific capacity of approximately 311 mAhg-1, while zinc electrodes prepared using ZnO powder synthesized from ZnCl2 and Zn(NO3)2.6H2O and 6 wt.% PEG exhibit high specific energy of 255 and 275 mAhg-1, respectively. The results suggest a relationship between binder loading and battery capacity, but in-situ analysis of microstructural evolution of zinc electrode during charge/discharge process is needed to confirm this relationship.Article Citation - WoS: 13Citation - Scopus: 14Robust Fluorinated Siloxane Copolymers Via Initiated Chemical Vapor Deposition for Corrosion Protection(Springer, 2021) Cihanoğlu, Gizem; Ebil, ÖzgençHomopolymers of 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4D4), 2-(perfluorohexyl)ethyl acrylate (PFHEA) and 2-(perfluoroalkyl)ethyl methacrylate (PFEMA) and their copolymers were synthesized via initiated chemical vapor deposition (iCVD). All coatings exhibited excellent adhesion to substrates. The corrosion resistance of iCVD coatings was investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. In addition, chemical durability of various organic solvents and adhesion to the substrate were also evaluated. Tafel polarization measurements in 5 wt% NaCl solution revealed that the corrosion rates as low as 0.002 mpy on zinc substrates can be reached with 250-nm-thick iCVD-synthesized polymers which is lower than previously reported polymer coatings and more than three orders of magnitude lower than bare zinc. EIS analysis coupled with equivalent electric circuits model confirmed that poly(V4D4) and poly(PFHEA) homopolymers show extremely high protection efficiencies (similar to 99%) on zinc, while poly(V4D4-co-PFHEA) copolymer with slightly lower corrosion efficiency (85-91%) provides a better anticorrosion barrier with weight loss reduction by 57 and 45% for copper and zinc, respectively, and with improved chemical and mechanical properties. The results indicate that iCVD process enables fabrication of finely tuned fluorinated siloxane copolymer conformal coatings for corrosion protection on a variety of substrates.