Browsing by Author "Özel, Faruk"

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Atomik Olarak Dizayn Edilmiş Farklı Kompozisyonlardaki Nano-çubuksu Maddelerin Sentezlenmesi ve Fotoelektrik Özelliklerinin İncelenmesi
(Konya Teknik Üniversitesi, 2021) Sarılmaz, Adem; Akyıldız, Hasan; Özel, Faruk
Nano-parçacıkların şekil ve kompozisyon değişimlerine bağlı üretimleri, birçok farklı uygulamada yüksek performanslı yapılar oluşturulması için temel teşkil etmektedir. Hali hazırda literatürde fazlaca kullanımı rapor edilen inorganik yarıiletken parçacıkların farklı şekil ve kompozisyonlarda üretilmesi, üretim yöntemlerinin geliştirilmesi ve optimize edilmesi de aynı şekilde hayati önem arz etmektedir. İnorganik yarıiletken parçacıklar arasında da nano-kalkojenitler, elementlerinin zehirli olmaması ve doğada bol bulunabilir olması gibi bazı özelliklerinden dolayı enerji uygulamalarında önemli bir yere sahiptir. Bu tez çalışmasında, diğer birçok yönteme göre kolay ve hızlı olarak kabul edilen sıcak besleme yöntemi ile dörtlü Cu2BSnS4 (B: Zn, Ni, Co, Mn) ve üçlü CuxBySz parçacıkları, şekil ve faz yapıları kontrol edilerek başarılı bir şekilde sentezlenmiştir. Ayrıca bu malzemelerin çok duvarlı karbon nanotüpler (MWCNT) ile kompozit üretim denemeleri gerçekleştirilmiştir. Sentezlenen nanoparçacıklar boya duyarlı güneş hücrelerinde karşıt elektrot olarak kullanılmış ve üretilen güneş hücrelerinin performansları, referans elektrot olan platin ile kıyaslanarak yorumlanmıştır. Elde edilen sonuçlardan sentezlenen parçacıkların Pt ile kıyaslanabilecek seviyede verimler elde edildiği gözlemlenmiştir. Sonuç olarak, bu tez çalışmasında birçok farklı kompozisyon ve şekillerde nano-parçacıklar sıcak besleme yöntemi ile başarılı bir şekilde sentezlenmiş ve elde edilen bu parçacıkların güneş hücresi uygulamalarında platine alternatif malzemeler olarak kullanılabilecekleri gösterilmiştir.
Citation - WoS: 17
Citation - Scopus: 18
Carbon Nanotube Supported Thiospinel Quantum Dots as Counter Electrodes for Dye Sensitized Solar Cells
(PERGAMON-ELSEVIER SCIENCE LTD, 2021) Sarılmaz, Adem; Özen, Abdurrahman; Akyıldız, Hasan; Gültekin, Şirin Siyahjani; Kuş, Mahmut; Özel, Faruk
In the current study, sulfide based ternary and quaternary thiospinel nanocrystals were synthesized by using a simple hot injection method and used as catalyst instead of Pt in a DSSCs application for the first time. CuNiCoS4, CuCo5S8, and CuCo2S4 as thiospinel nanocrystals have been synthesized in crystalline structure, single phase, nearly stoichiometric, and having narrow size distribution below 10 nm. Comparative studies showed that, Carbon Nanotube (CNT)-CuCo2S4 based DSSCs yielded the most favorable results as a potential counter electrode showing very similar power conversion efficiency (eta = 4.99%) in comparison with Pt based DSSCs produced under identical conditions. Therefore, this study implies that the thiospinel nanocrystals and their CNT supported composites can be proposed as novel counter electrode materials for low-cost platinum-free solar cells.
Citation - WoS: 8
Citation - Scopus: 8
Molecular Engineering-Device Efficiency Relation: Performance Boosting of Triboelectric Nanogenerator Through Doping of Small Molecules
(Wiley, 2022) Yigit Arkan, Mesude Z.; Kinas, Zeynep; Arkan, Emre; Gökçe, Celal O.; Kara, Koray; Karabiber, Abdülkerim; Özel, Faruk; Kuş, Mahmut
Triboelectric nanogenerators (TENGs) are promising new generation systems with their basic motion-based working principle using both triboelectric and electrostatic effects. Today, the energy densities of TENGs are insufficient for many electronic devices and new strategies are needed to increase their power conversion efficiency. In this study, two different Perylene-based organic structures were added to the triboelectric layers as well as the electrochemical properties of these structures, and the device parameters related to these properties were investigated. A large variety of instrumental analyses, including cyclic voltammetry, contact angle, scanning electron microscopy, atomic force microscopy, and so on, have been used to identify the relationship between doped molecules, their doping ratios, and obtained fiber structures. Depending on molecular structure and even any small variations in side groups of molecules, different doping rates brought about various device outputs. Compared with undoped layers, doping of small molecules led to a similar to 3.3 times increase in the maximum power of the best-performed devices, and a very high voltage value of 500 V was obtained. The analysis of doping with small molecules undertaken here has extended our knowledge of how material design improves the electrical output and contributes to the device performance in TENGs.
Citation - WoS: 12
Citation - Scopus: 13
Photodeposition of Molybdenum Sulfide on Mtio3 (m: Ba, Sr) Perovskites for Photocatalytic Hydrogen Evolution
(Elsevier Science Sa, 2023) Kuru, Talha; Yanalak, Gizem; Sarilmaz, Adem; Aslan, Emre; Keles, Ali; Genç, Munevver Tuna; Özel, Faruk
Photocatalytic hydrogen evolution using by semiconductor materials have been studied effectively by converting solar energy into the chemical energy. Perovskite-based materials have been widely used as semiconductor catalysts for the photocatalytic hydrogen production. Herein, molybdenum sulfide photodeposited onto MTiO3 (M: Ba, Sr) perovskites (MTiO3/MoSx) have been investigated on the photocatalytic hydrogen evolution under solar light irradiation in the presence of triethanolamine (TEOA) and eosin Y (EY) as an electron donor and photosensitizer, respectively. Compared to pristine MTiO3, BaTiO3/MoSx and SrTiO3/MoSx show a remarkable improvement in the hydrogen production efficiency and stability. Photocatalytic hydrogen evolution activities found in the order of SrTiO3/MoSx > BaTiO3/MoSx > MoSx > SrTiO3 > BaTiO3. In addition, photocatalytic hydrogen activity of SrTiO3/Pt was evaluated for comparison with SrTiO3/MoSx under the same conditions and SrTiO3/MoSx produced higher hydrogen activity than SrTiO3/Pt due to the high active sites created by MoSx on the catalyst surface which is originated from Mo-S and S-S bonds.
Citation - WoS: 6
Citation - Scopus: 12
Refractory-Metal Chalcogenides for Energy
(Wiley-V C H Verlag Gmbh, 2022) Özel, Faruk; Arkan, Emre; Coşkun, Halime; Deveci, İlyas; Yıldırım, Murat; Yıldırım, Mehmet; Ersöz, Mustafa; Kuş, Mahmut
When it is asked, where can refractory metals be used?, the possible shortest answer is, where cannot they be used? The uses of refractory-metal-based compounds in research and industry are too many to be enumerated; nevertheless, some outstanding examples are briefly mentioned here. Essentially, chalcogenide forms of refractory metals are preferred in the fabrication of high-performance structures. Therefore, expanding the current studies that usually focus on tungsten- and molybdenum-based structures to other materials may open new opportunities. Moreover, research on ternary and quaternary structures can also be a keystone in creating high-performance products. The rationale of the present review is to give a brief overview of the recent history of refractory-metal-based chalcogenides (RMCs). Initially, the framework is confined to the general design and approaches for the synthesis of refractory metal chalcogenides. The assay is continued by extending with characteristic features of materials from crystalline properties to thermoelectric attributes and examining device fabrication processes. Taken together, the device fabrication part where RMCs are mainly used is extensively focused upon. Finally, outlook and future perspectives are given on the design and construction of RMCs to enable future inspiration and innovation.
Citation - WoS: 14
Citation - Scopus: 14
Ternary and Quaternary Thiospinel Nanocrystals With Adjustable Compositions: Effects of Band-Gaps and Nanostructures on Visible-Light Photocatalytic H-2 Evolution
(ELSEVIER SCI LTD, 2020) Sarılmaz, Adem; Yanalak, G.; Aslan, E.; Akyıldız, Hasan; Patir, I. H.; Özel, Faruk
Ternary and quaternary structured thiospinel nanocrystals are important materials for energy applications based on their outstanding characteristics such as earth abundant components, non-toxic nature and simple production. In this study, CuNiCoS4, CuCo5S8 and CuCo2S4 nanocrystals have been successfully synthesized via hot injection-method with generalized synthesis conditions and detailed structural, optical and electrochemical characterizations were performed for the first time. The characterization results indicated that the nanocrystals were single phase, nearly stoichiometric composition and a mean size below 10 nm. Moreover, the synthesized nanocrystals have been used for the photocatalytic hydrogen evolution as a catalyst under visible light irradiation. In these reactions, CuNiCoS4 nanocrystals exhibited higher photocatalytic activity and stability than the others. CuNiCoS4 and CuCo5S8 catalyst have firstly been proven as valuable alternatives to CuCo2S4 structure and Platinum in hydrogen evolution reactions and are of particular interest due to lower costs, ease of fabrication and comparable evolution performance. (C) 2020 Elsevier Ltd. All rights reserved.
Citation - WoS: 16
Citation - Scopus: 16
Ternary Cuco2s4 Thiospinel Nanocrystal-Coated Photodiode With Improved Photoresponsivity and Acceptance Angles for Optoelectronic Applications
(SPRINGER, 2020) Yıldırım, Murat; Koçyiğit, Adem; Sarılmaz, Adem; Özel, Sultan Süleyman; Kuş, Mahmut; Özel, Faruk
Ternary-structured thiospinels have attracted great attention in recent years for energy applications due to their attractive characteristics such as simple production, earth-abundant components and non-toxic nature. In this work, copper cobalt sulfide (CuCo2S4 or carrollite) thiospinel nanocrystals were synthesized by a hot-injection method, and detailed electrical and optoelectronic characterizations were performed in a Schottky device. The synthesized nanocrystals were used as an interfacial layer between the Au metal and p-Si semiconductor to obtain an Au/CuCo2S4/p-Si device. The structural and morphological characterizations confirmed the crystallinity, nanostructure and composition of the CuCo2S4 nanocrystals. The I-V and C-V measurements were employed to characterize the Au/CuCo2S4/p-Si device for various illumination intensities. The obtained device exhibited good rectifying and photodiode properties as well as good photocapacitance. The Au/CuCo2S4/p-Si device can be used and improved for optoelectronic applications.