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Keeping global warming at 2 degrees and below as stated in the Paris Climate Agreement and minimizing emissions can only be achieved by establishing a hydrogen (H-2) ecosystem. Therefore, H-2 technologies stand out in terms of accomplishing zero net emissions. Although H-2 is the most abundant element in the known universe, molecular H-2 is very rare in nature and must be produced. In H-2 production, reforming natural gas and renewable hydrogen processes using electrolyzers comes to the fore. The key to all these technologies is to enhance production speed, performance, and system lifetime. At this point, composite membranes used in both processes come to the fore. This review article summarizes composite membrane technologies used in methane, ethanol, and biomass steam reforming processes, proton exchange membranes, alkaline water electrolysis, and hybrid sulfur cycle. In addition to these common H-2 production technologies at large quantities, the innovative systems developed with solar energy integration for H-2 generation were linked to composite membrane utilization. This study aimed to draw attention to the importance of composite membranes in H-2 production. It aims to prepare a guiding summary for those working on membranes by combining the latest and cutting-edge studies on this subject., T?rkiye Bilimsel ve Teknolojik Arastirma Kurumu [122M037]; TUBITAK, The authors would like to acknowledge the partial financial support of TUBITAK under research contract number 122M037.

Research on supercapacitors has recently shifted its attention to the development of low-cost electrode materials with long-cycle stability. It has been thought that titanium dioxide, an important semiconductor material with strong chemical stability and a low cost, is a potential material for capacitors1 . During charging and discharging processes, TiO2 frequently exhibits poor electrical conductivity and agglomeration2 . The overall strategy is to combine conductive carbon-based materials to create hybrid materials to improve their performance3 . g-C3 N4 is a stable allotrope of C3 N4 and it has been gaining more attention for some time. This material is a good alternative for building hybrid systems, and it has optical, electrical, and structural properties that make it a multi-functional material4 and enhances the performance of supercapacitors5 . TiO2 /C3 N4 hybrid material created in this study using an effective, inexpensive, and simple thermal process and utilized as supercapacitor electrodes by using aqueous LiCl/PVA electrolyte. Supercapacitor has shown specific capacitance, power density, and Coulombic efficiency as high as 20.6F.g1, 63Wh.kg-1 and 92% respectively. TiO2 /C3 N4 hybrid materials outperform TiO2 in terms of electrochemical performance.

In this book, you will have the opportunity to have comprehensive knowledge about the use of energy from the sun, which is our source of life, by converting it into different chemical fuels as well as catching up with the latest technology. The most important obstacle to solar meeting all our energy needs is that solar energy is not always accessible and, therefore, cannot be used when needed. Consequently, the conversion of solar energy into chemical energy, which has become increasingly important in recent years, is a groundbreaking topic in the field of renewable energy. This type of chemical energy is called solar fuel. Hydrogen, methanol, methane, and carbon monoxide are among the solar fuels, which can be produced via solar-thermal, artificial photosynthesis, photocatalytic or photoelectrochemical routes. Solar Fuels compiles the objectives related to the new semiconductor materials and manufacturing techniques for solar fuel generation. Chapters are written by distinguished authors who have extensive experience in their fields. A multidisciplinary contributor profile, including chemical engineering, materials science, environmental engineering, and mechanical and aerospace engineering provides a broader point of view and coverage of the topic. Therefore, readers absolutely will have a chance to learn about not only the fundamentals, but also the various aspects of materials science and manufacturing technologies for solar fuel production. Moreover, readers from diverse fields should take advantage of this book to comprehend the impacts of solar energy conversion in chemical form. Audience The book will be of interest to a multidisciplinary group of fields in industry and academia, including physics, chemistry, materials science, biochemical engineering, optoelectronic information, photovoltaic and renewable energy engineering, electrochemistry, electrical engineering, and mechanical and manufacturing engineering.

The production of photodetectors that can provide their own power needs and can be adapted to different application conditions is very important for next-generation optoelectronic devices. Three-dimensional (3D) ZnO in nanoflower (NF) morphology was synthesized to be sensitized with all-inorganic perovskite for the application of self-powered photodetector (PD) devices. Consequently, we report high-performance and air-/solvent-stable ZnO/CsPbBr3/S-g-C3N4-based PD devices in three different forms: as a solid-state form and photoelectrochemical (PEC)-type PDs in both liquid electrolyte systems and a quasi-solid-state (QSS) form. The solid-state configuration of the PD device generated a photocurrent density of 150 mu A at 367 nm, while the detectivity and responsivity values were calculated as 3.4 x 10(15) Jones and 0.25 AW(-1), respectively. The device was confirmed to be air-stable upon stability tests for 90 days, retaining more than 65% of its initial current density. The self-power ability of ZnO/CsPbBr3/S-g-C3N4 PEC-type PDs was proven for both liquid electrolyte systems and QSS forms. Open cell voltage and sensitivity as high as 250 mV and 3.96 x 10(7)%, respectively, were obtained for QSS ZnO/CsPbBr3/S-g-C3N4 PEC-type PDs. This study proved that the ZnO/CsPbBr3/S-g-C3N4-based PEC PD devices with high performance in the range of 367 to 460 nm can be adapted to meet different application requirements in a wide range from liquid electrolyte systems to solid- and QSS-type electrolyte systems., T?rkiye Bilimsel ve Teknolojik Arastirma Kurumu [118C551]; TUBITAK, C.T.A., N.D.S., and M.S. would like to acknowledge the partial financial support from TUBITAK under research contract number 118C551.

Research on supercapacitors has recently shifted its attention to the development of low-cost electrode materials with long-cycle stability. It has been thought that titanium dioxide, an important semiconductor material with strong chemical stability and a low cost, is a potential material for capacitors1 . During charging and discharging processes, TiO2 frequently exhibits poor electrical conductivity and agglomeration2 . The overall strategy is to combine conductive carbon-based materials to create hybrid materials to improve their performance3 . g-C3 N4 is a stable allotrope of C3 N4 and it has been gaining more attention for some time. This material is a good alternative for building hybrid systems, and it has optical, electrical, and structural properties that make it a multi-functional material4 and enhances the performance of supercapacitors5 . TiO2 /C3 N4 hybrid material created in this study using an effective, inexpensive, and simple thermal process and utilized as supercapacitor electrodes by using aqueous LiCl/PVA electrolyte. Supercapacitor has shown specific capacitance, power density, and Coulombic efficiency as high as 20.6F.g1, 63Wh.kg-1 and 92% respectively. TiO2 /C3 N4 hybrid materials outperform TiO2 in terms of electrochemical performance.

In conventional batteries, the storage takes place in the static solid electrode. The storage capacity is directly proportional to the volume of the electrodes and hence, the energy storage capacity is limited. Redox flow batteries, in which energy is stored in liquid electrolytes, have large-scale energy storage capacity. The storage capacity is directly related with the electrolyte volume, concentration and redox couple, whereas the power density is determined by the electrode area and current density. Properties such as flexible design, high efficiency and long lifetime make the redox flow battery a substantial storage method. Various redox couples have been studied to date, and vanadium redox flow battery has found one of the most prominent among them. Unlike other redox couples, the use of the same type of redox couples (V2+-V3+ and V4+-V5+) in the anolyte and catholyte brings many advantages. Vanadium redox flow batteries are generally used to store solar energy. The conversion and storage of solar energy in different systems creates a low-efficiency integration problem by increasing the cost and complicating the system. Due to this problem, the conversion and storage of solar energy in a single system has become a popular research topic. In this system, by integrating the Vanadium redox flow cells with the photoelectrochemical cell, the sunlight absorbed by the photoelectrode is converted into electrochemical energy. Simultaneously, it can be stored in the cell in the form of chemical energy. In the first chapter of the thesis, moderate band gap and non-toxic indium sulfide (In2S3) and hybrid titanium dioxide-indium sulfide (TiO2-In2S3) semiconductors are integrated as photoelectrode materials into the solar vanadium redox flow batteries. The dense and mesoporous layer of TiO2 semiconductor have been deposited via RF magnetron sputtering and spin coating method, respectively. On the other hand, the In2S3-based photoelectrodes have been fabricated via the ultr, Geleneksel bataryalarda depolama, statik katı elektrotta gerçekleşmektedir. Depolama kapasitesinin elektrotların hacmi ile doğru orantılı olması nedeniyle enerji depolama kapasitesi sınırlıdır. Enerjinin sıvı elektrolitlerde depolandığı redoks akış bataryaları ise büyük ölçekli enerji depolama kapasitesine sahiptir. Depolama kapasitesi, elektrolit hacmi, konsantrasyonu ve redoks çiftlerinin çeşidi ile, güç yoğunluğu ise elektrot alanı ve akım yoğunluğuyla belirlenmektedir. Esnek tasarım, yüksek verimli ve uzun ömürlü olması gibi özellikleri redoks akış bataryasını önemli bir depolama yöntemi yapmaktadır. Günümüze kadar birçok farklı redoks çiftleri üzerinde çalışmalar yapılmakla birlikte, bunlardan en dikkat çekeni vanadyum redoks akış bataryası olmuştur. Diğer redoks çiftlerinin aksine, anolitte ve katolitte aynı türden redoks çiftlerinin (V2+-V3+ ve V4+-V5+) kullanılması birçok avantajı beraberinde getirmektedir. Vanadyum redoks akış bataryaları genellikle güneş enerjisini depolamak için kullanılmaktadır. Güneş enerjisinin dönüşümünün ve depolamasının farklı sistemlerde gerçekleşmesi maliyeti arttırmakta, ayrıca sistemi kompleksleştirerek düşük verimli entegrasyon sorunu oluşturmaktadır. Bu soruna istinaden, güneş enerjisinin dönüşümü ve depolanmasının tek bir sistemde meydana gelmesi, enerji araştırma ve uygulamaları alanında ivme kazanan bir konu haline gelmiştir. Vanadyum redoks akış bataryalarının fotoelektrokimyasal hücre ile birleşimiyle, fotoelektrotun soğurduğu güneş ışığı elektrokimyasal enerjiye dönüştürülmektedir. Eş zamanlı olarak aynı sistemde kimyasal enerji formunda depolanabildiği görülmektedir. Bu kapsamda gerçekleştirilen tez çalışmasında ilk olarak, solar vanadyum redoks akış bataryalarına dar bant aralığına sahip ve toksik olmayan indiyum sülfür (In2S3) ve hibrit titanyum dioksit-indiyum sülfür (TiO2-In2S3) yarı iletkenleri entegre edilmiştir. TiO2 yarı iletkenin yoğun katmanı saçtırma, mezofor katmanı spin kaplama yöntemi ile üretilmiştir. In2

Fotovoltaik günes pilleri, toplam elektrik üretimine her geçen yıl daha fazla katkı saglayarak yenilenebilir enerji kaynakları arasındaki yerini saglamlastırmaktadır. Fotovoltaik günes pillerinin bu hızlı yükselisi temel anlamda iki parametreye baglıdır. Bunlar, yarıiletken malzemelerin iyilestirilmesi/gelistirilmesi ve yarıiletken ince film üretim tekniklerinin iyilestirilmesi/gelistirilmesi olarak sıralanabilir. Bu kapsamda yapılan çalısmalar ile, laboratuvar skalasında günes pili verimleri %46?ları bulmus, ayrıca enerji-geri-dönüsüm zamanları da 1 yıl civarına gerilemistir. Fotovoltaiklerin toplam enerji üretimine olan katkısının daha da artması için maliyet/performans oranının düsürülmesi kritiktir. Bu kapsamda solüsyon tabanlı üretim yöntemleri, klasik vakum tabanlı üretim yöntemlerine kıyasla çok daha düsük maliyet avantajı ile karsımıza çıkmaktadır. Bu projede CuInGa(S,Se), perovskit ve bu yapılardan olusan tandem günes pilleri maliyet etkin solüsyon tabanlı üretim yöntemleri ile üretilmistir. Bu dogrultuda sogurucu ve tampon tabakaların üretiminde sprey piroliz ve dönel kaplama yöntemleri kullanılmıstır. Sprey piroliz, diger solüsyon tabanlı üretim yöntemlerine kıyasla çok daha az solüsyon tüketmesi, stokiyometri kontrolünün kolaylıgı, genis alanlara kolay adapte edilebilmesi gibi avantajlar ile ön plana çıkmaktadır. Perovskit tabanlı günes pillerinde elektron iletim tabakası (ETL) olarak kullanılan titanyum dioksite (TiO2) alternatif olusturan çinko oksit (ZnO) nanoyapılar proje kapsamında kimyasal banyo yöntemi ile sentezlenmis ve bu yapıların günes pili performansına olan etkileri ayrıntılı bir sekilde çalısılmıstır. 3D ZnO nanoyapıların 1D ZnO nanoyapılara kıyasla daha yükse foto çevrim verimi sagladıgı saptanmıstır. Proje kapsamında hem sogurucu hem de tampon tabakaların sprey piroliz ile üretildigi ZnO-NG/CIGS/InS yapılı fotoelektrokimyasal günes pillerinde en yüksek dıs kuvantum verimi 382 nm dalgaboyunda % 83 olarak hesaplanmıstır. Projede farklı ABX

Yakıt pili teknolojisi, hidrojen enerjisini en ekonomik ve verimli kullanan teknolojilerden bir tanesidir. Kullandığı yakıt ve üretebildiği güç bakımından çeşitli yakıt pilleri mevcuttur. Bu yakıt pilleri içerisinde polimer elektrolit membranlı yakıt pillerinin (PEMYP) en çok gelecek vaad ettiği öngörülmektedir. Bu tez çalışmasında tek hücreli bir polimer elektrolit membranlı yakıt pili Comsol Multiphysics programı kullanılarak iki boyutlu olarak modellenmiştir. Akışa paralel model oluşturulmuştur. Akış kanalına farklı geometrilerde engeller konularak daha fazla yakıtı reaksiyona zorlamak hedeflenmiştir. Bu şekilde ideal performans değerlerine yakın akım ve güç yoğunlukları oluşturulmaya ve kayıpları en aza indirmeye çalışılmaktadır. Sınır koşulları olarak değişik hız değerleri girilmiştir. Bu şekilde debiyi sabit tutmak hedeflenmiştir. Ayrıca çıkış sınır şartları için farklı basınç değerleri verilerek performans etkisi araştırılmıştır. Yapılan çalışmalar sonucu görülmüştür ki; giriş hızının artması, çıkış basıncının artması, katot tarafındaki sınır şartlarına anoda göre daha fazla oksidant beslenmesi ve kanal boyunca bulunan engellerin derinliğinin artması sonrasında yakıt hücresi performansları artmıştır., Fuel cell technology is one of the most economic and efficient ways to utilize hydrogen energy. Various types of fuel cells are present regarding the fuel type and amount of produced power. Among those, proton exchange membrane fuel cells (PEMFCs) are very promising. In this thesis work, a 2D proton exchange membrane fuel cell unit cell was modeled using Comsol Multiphysics software. Cell section was taken parallel to flow direction. Obstacles with various geometries were placed on the flow channel in order to force more amount of reactant species to react. By doing that, values of current and power densities that are close to ideal performance were tried to be approached and losses were tried to be minimized. As boundary conditions, several inlet velocities were applied. By doing so, reactant flow rate was aimed to be kept constant. Also, the effect of setting different pressure values at the outlet on performance was investigated. Consequently, it was observed that increasing inlet velocity and outlet pressure, feeding more reactant at the cathode compared to the anode and increasing the depth of the obstacles placed through the channel enhanced the fuel cell performance.

Copper-based ternary Cu(In,Ga)S-2 (CIGS) nanoparticles (Np) in chalcopyrite crystal phase have been synthesized via hot-injection method to be used as colloidal Np ink for 3D-ZnO nanosheet thin film sensitization for the enhancement of light absorption in the visible region due to its suitable bandgap. Additionally, an indium sulfide (In2S3) layer has been deposited on the 3D-ZnO/CIGS thin-film for surface modification of CIGS layer to protect against photocorrosion, and bare 3D-ZnO for constructing suitable band alignment in photoelectrochemical water splitting (PEC) applications for hydrogen production. The 3D-ZnO/In2S3 photoelectrode generated the photocurrent density (J) of - 1.1 mA.cm(-2) (at 1.2 V vs. RHE) and an incident photon to-current efficiency (IPCE) of 35.0% at 382 nm. On the other hand, after incorporation of CIGS-Np between 3D-ZnO NS and In2S3 layers, 2.2 mA.cm(-2) of J (at 1.2 V vs. RHE) and 53.2% IPCE at 382 nm have been observed.

For the first time with this study, membranes from directly copolymerized disulfonated poly(arylene ether sulfone) (BPSH 35) were utilized to replace NafionTM in vanadium redox flow batteries (VRFB). Direct copolymerization provided exact control of the degree of disulfonation on the chemical structure. BPSH 35 showed higher proton conductivity (75 mS cm-1), lower vanadium permeability (1.6x10-13 m2 s-1) and better selectivity (4.7x1013 S m-3 s) than N212. The water uptake values for N212 and BPSH 35 membranes were 28 and 40 % by weight, respectively. Higher proton conductivity and water uptake were observed due to the higher ion exchange capacity (IEC) values of BPSH35. In spite of high water uptake of BPSH35, it showed better resistance to vanadium permeation which was most probably because of the chemically bulky nature of the membrane. Moreover, higher columbic (98.9 %) and energy efficiencies (75.6-90.3 %) at the considered current densities than N212 were achieved. Consequently, BPSH 35 membranes were successfully demonstrated as an inexpensive energy efficient candidate for VRFB.

Fosil yakıtların hızlı ve sürekli tükenmesinden dolayı bilim insanları araştırmalarını yenilenebilir enerji kaynaklarına odaklamıştır. Yenilenebilir enerji kaynakları (Güneş, rüzgar vb.) sıfır emisyona sahip olduğundan dolayı küresel ısınmayla mücadele konusunda çok büyük öneme sahiptir. Diğer yandan, güneş ve rüzgar enerjileri üretim esnasında dalgalanmalara sebep olduğundan dolayı şebeke istikrarsızlığı ve düşük güvenilirlik sorunlarını beraberinde getirmektedir. Bu gibi sorunları aşmak için tercih edilen yöntem ihtiyaç fazlası enerjinin üretildiği durumlarda bu enerjinin depolanarak, enerji talebinin en yoğun olduğu zamanlarda dahi depodan şebekeye beslenmesidir. Bu noktada depolama sistemlerinin verimliliği ve maliyetleri çok önemlidir. Depolama sistemlerinden bir tanesi olan akış bataryaları bu konuda iyi bir alternatiftir. Vanadyum redoks akış bataryaları uzun ömürleri ve yüksek enerji verimliliğinden dolayı diğer akış batarya sistemlerine göre daha avantajlıdır. Bu sistemin kullanımının yaygınlaşmasına engel olan en önemli sorunlar, yakıtları birbirinden ayıran Nafion? zarlarının ve yakıt olarak kullanılan vanadyum elektrolitlerinin maliyetlerinin yüksek olmasıdır. Bu sorunları aşmak ve daha iyi performans elde edebilmek için bu proje kapsamında Nafoon?alternatif zarlar geliştirilmiş ve bu zarların VRAB performnsaları başarılı bir şekilde test edilmiştir. Ayrıca bu zarların yapılan testleri sonucunda elde edilen verimlerinin Nafion? zarlarının kullanıldığı vanadyum akış bataryalarından çok daha iyi olduğu gözlemlenmiştir. Bu çalışmada aynı zamanda su tutumu, proton iletkenliği, iyon değiştirme kapasitesi vanadyum iletkenliği gibi kritik membran parametrelerin VRAB performansı üzerine etkileri araştırılmıştır.

Robust, cost-effective, and scalable solution based chemical bath deposition and ultrasonic spray pyrolysis methods have been applied to fabricate one dimensional (1D) zinc oxide nanowire (ZnO NW) and zinc stannate (ZTO) heterojunction thin films to be employed in photoelectrochemical (PEC) water splitting and UV photodetector (PD) systems. PEC performance evaluation in a three-electrode cell confirmed the positive effect of ZTO on ZnO NW-based photoanode enhancing incident photon-to-current efficiency (IPCE%) two-folds of the pristine ZnO NW at 367 nm wavelength. Responsivity (Rs) and detectivity (D*) values of the pristine ZnO NW-based PD have been increased from 0.5 A.W?1 and 0.5 × 1012 Jones to 1.7 A.W?1 and 1.0 × 1012 Jones with ZTO layer, respectively. © 2022 Elsevier B.V., This research was supported by TUBITAK-BIDEB-2218 Program No.118C551., 118C551

This study reports a seeding-layer free synthesis of nanostructured three-dimensional zinc oxide (3D-ZnO) thin films via a simple and cost-effective chemical bath deposition method (CBD) followed by their sensitization with inorganic perovskite halide semiconductors for luminescence-based applications. The emission abilities of pristine ZnO nanostructures have been enhanced with the incorporation of CsPbBr3 in the cubic crystal phase, which is proven to be a highly stable member of the inorganic halide perovskite family. Additionally, the transformation of CsPbBr3 nanocrystals into Cs4PbBr6-CsPbBr3 composite structure has been attained by altering the (i) CsBr content and (ii) crystallization temperature during the perovskite synthesis step, resulting in a remarkable luminescence increase for the overall structure by -17 folds. A detailed evaluation of defect contents and carrier lifetimes of pristine and perovskite deposited ZnO thin films have been conducted via time-resolved photoluminescence spectroscopy showing an improved electron transfer especially for Cs4PbBr6-CsPbBr3 deposited ZnO thin films., Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [315M348], This study was supported by The Scientific and Technological Research Council of Turkey (TUBITAK) under the research grant 315M348. Also, the authors would like to thank Hadi Jahangiri from KOC University Surface Science and Technology Center for performing the time-resolved photoluminescence measurements.

Bu çalışmada, COMSOL® ticari yazılımı kullanılarak, tek hücreli PEM tipi bir yakıt pilinin, iki ve üç boyutlu, izotermal, tek fazlı ve kararlı haldeki modelleri oluşturulmuştur. Oluşturulan modellerde, paralel akış kullanılmıştır. Modelde, elektron akımının iletken katı kısımdan iletimi, gazların akış kanallarındaki transferi ve su molekülleri ile iyonların polimer elektrolit zardan taşınımı bulunmaktadır. Akış kanallarındaki türlerin, gaz akışı sıkıştırılamaz Navier-Stokes denklemleri ile Brinkman denklemlerinin birlikte kullanılması ile çözülürken, su ve iyon transferi genelleştirilmiş Maxwell-Stefan denklemleri ile çözülmektedir. Bu araştırma esas olarak, pil geometrisi, sıcaklığa bağlı olarak değişen zarın iyonik iletkenliği, denge akım yoğunluğu ve difüzyon katsayıları gibi parametrelerin yakıt pili performansına olan etkilerini ortaya çıkarmak için yapılmıştır. Bunu başarabilmek için modeller, farklı denge akım yoğunluğu, zar iyonik iletkenliği ve difüzyon katsayılarında ve farklı geometrilerde çözülmüştür. Bu çalışmada hidrojen, oksijen ve suyun farklı sıcaklık ve hücre çalışma potansiyellerindeki kütle dağılımları da incelenmiştir. Sonuçlara göre; performans, sıcaklık arttıkça artan denge akım yoğunluğu, zarın iyonik iletkenliği ve difüzyon katsayılarının artmasıyla, artmaktadır. Ayrıca, geometrinin performansa olan etkisini belirlemek için iki farklı geometride üç boyutlu modeller oluşturulmuş ve bu modellerin karşılaştırılması yapılmıştır. Bu modellerden biri düz kanal geometrisine, diğeri ise silindirik kanal geometrisine sahiptir. Güç yoğunluğunun en yüksek olduğu hücre çalışma potansiyeli değerlerinde(0,4-0,6 V), silindirik modelden 25 ?C'de, 0,58-0,93 A/cm2 aralığında, 80 ?C'de ise 0,82-1,05 A/cm2 aralığında akım yoğunluğu elde edilmiştir. Düz modelde ise aynı çalışma potansiyeli değerlerinde 25 ?C'de, 0,54-0,84 A/cm2 aralığında, 80 ?C'de ise 0,75-0,95 A/cm2 aralığında akım yoğunluğu elde edilmiştir., In this study, 2-D and 3-D steady state, isothermal, and one-phase numerical models of a single Proton Exchange Membrane Fuel Cell were built by using COMSOL Multiphysics® software. A parallel-to-flow model of a single cell was used as the modeling domain. The model consisted of the delivery of electrical current in solid phase, transportation of gases in the flow channels, and transmission of water and ions in the polymer electrolyte membrane. The gas flow of the reactants in the channels was solved by incompressible Navier-Stokes equations with Brinkman equation while water and ion transportation was solved by generalized Maxwell-Stefan equations. The investigation was mainly focused on effects of the geometry and the effects of the parameters that are related with temperature, such as exchange current density, ionic conductivity and diffusivity values. To achieve that, 2-D and 3-D parallel-to-flow models with different exchange current density, ionic conductivity and diffusivity values and different geometries were solved. Mass fraction distribution of hydrogen, oxygen, and water were examined at different temperature and voltage values. It was pointed out from the results that increasing exchange current density, ionic conductivity and diffusivity values results in better performance. To determine the effect of geometry two models with different geometries were built and solved. One of the models has planar channel geometry while the other has cylindrical channel geometry. At middle cell potential values where the power density is high, the current density that is obtain from cylindrical model is between 0.58-0.93 A/cm2 at 25 ?C and 0.82-1.05 A/cm2 at 80 ?C. At same cell potential values, the current density that is obtain from planar model is between 0.54-0.84 A/cm2 at 25 ?C and 0.75-0.95 A/cm2 at 80 ?C.

For the first time with this study, membranes from directly copolymerized disulfonated poly(arylene ether sulfone) (BPSH 35) were utilized to replace NafionTM in vanadium redox flow batteries (VRFB). Direct copolymerization provided exact control of the degree of disulfonation on the chemical structure. BPSH 35 showed higher proton conductivity (75 mS cm-1), lower vanadium permeability (1.6x10-13 m2 s-1) and better selectivity (4.7x1013 S m-3 s) than N212. The water uptake values for N212 and BPSH 35 membranes were 28 and 40 % by weight, respectively. Higher proton conductivity and water uptake were observed due to the higher ion exchange capacity (IEC) values of BPSH35. In spite of high water uptake of BPSH35, it showed better resistance to vanadium permeation which was most probably because of the chemically bulky nature of the membrane. Moreover, higher columbic (98.9 %) and energy efficiencies (75.6-90.3 %) at the considered current densities than N212 were achieved. Consequently, BPSH 35 membranes were successfully demonstrated as an inexpensive energy efficient candidate for VRFB.

Robust, cost-effective, and scalable solution based chemical bath deposition and ultrasonic spray pyrolysis methods have been applied to fabricate one dimensional (1D) zinc oxide nanowire (ZnO NW) and zinc stannate (ZTO) heterojunction thin films to be employed in photoelectrochemical (PEC) water splitting and UV photodetector (PD) systems. PEC performance evaluation in a three-electrode cell confirmed the positive effect of ZTO on ZnO NW-based photoanode enhancing incident photon-to-current efficiency (IPCE%) two-folds of the pristine ZnO NW at 367 nm wavelength. Responsivity (Rs) and detectivity (D*) values of the pristine ZnO NW-based PD have been increased from 0.5 A.W?1 and 0.5 × 1012 Jones to 1.7 A.W?1 and 1.0 × 1012 Jones with ZTO layer, respectively. © 2022 Elsevier B.V., This research was supported by TUBITAK-BIDEB-2218 Program No.118C551., 118C551

In this study, g-C3N4-TiO2 nanocomposite structure has been loaded with Co3O4 via electroless plating and thermal annealing to form Co3O4@g-C3N4-TiO2 catalyst material for H-2 generation from NaBH4 hydrolysis. The material characterizations of the fabricated catalyst have been performed before and after exposure to an aqueous NaBH4 solution to understand the changes in catalytic performance and material properties. The Arrhenius activation energies have been determined to be 58 kJ mol(-1). The hydrogen generation rates have been observed as 180 and 1200 mL min(-1) g(cat)(-1) for the catalyst hydrolysis of NaBH4 at 30 degrees C and 60 degrees C, respectively. The catalytic activity performed in NaBH4 solution exhibited good reusability., This work was supported by the Belarusian Republican Foundation for Basic Research (Project No. T19TYuB-004) and the Council for Scientific and Technological Research of Turkey (TUBITAK) (Project No. 119M030)., Belarusian Republican Foundation for Basic Research [T19TYuB-004]; Council for Scientific and Technological Research of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [119M030]

This study reports a seeding-layer free synthesis of nanostructured three-dimensional zinc oxide (3D-ZnO) thin films via a simple and cost-effective chemical bath deposition method (CBD) followed by their sensitization with inorganic perovskite halide semiconductors for luminescence-based applications. The emission abilities of pristine ZnO nanostructures have been enhanced with the incorporation of CsPbBr3 in the cubic crystal phase, which is proven to be a highly stable member of the inorganic halide perovskite family. Additionally, the transformation of CsPbBr3 nanocrystals into Cs4PbBr6-CsPbBr3 composite structure has been attained by altering the (i) CsBr content and (ii) crystallization temperature during the perovskite synthesis step, resulting in a remarkable luminescence increase for the overall structure by -17 folds. A detailed evaluation of defect contents and carrier lifetimes of pristine and perovskite deposited ZnO thin films have been conducted via time-resolved photoluminescence spectroscopy showing an improved electron transfer especially for Cs4PbBr6-CsPbBr3 deposited ZnO thin films., Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [315M348], This study was supported by The Scientific and Technological Research Council of Turkey (TUBITAK) under the research grant 315M348. Also, the authors would like to thank Hadi Jahangiri from KOC University Surface Science and Technology Center for performing the time-resolved photoluminescence measurements.

Temperature dependent electrical conductivity of the polyaniline-sulfonated poly(arylene ether sulfone) with 35 mol percent sulfonation (PANI-BPS35) composite films were investigated in the temperature range of 80-380 K. These composite films showed semiconductor behavior with the exponential variation of inverse temperature dependence of electrical conductivity. Calculated Mott's parameters showed that variable range hopping mechanism is the dominant transport mechanism for the carriers in low temperature region. Photoconductivity of the PANI-BPS35 composite films having 10, 20, and 40 weight percent conductive filler under various illumination intensities was also studied. Photocurrent of the composite films increased with increasing both polyaniline weight fraction and temperature. Finally, the effect of doping on both electrical conductivity and the photoconductivity of the composite films was investigated.

This article reports the chromium (VI) removal from water by preparing polyacrylonitrile-co-poly (2-ethyl hexylacrylate) (PAN(92)-co-P2EHA(8)) and polyaniline (PANI) nanoporous membranes at various PANI loadings. It was observed that chromium (VI) rejections of nanoporous membranes are highly concentration and pH dependent. Almost complete chromium removal (99.9%) with higher flux values (120-177 L m-2 h-1) was observed for nanoporous membranes. Moreover, nanoporous membranes were also demonstrated as fouling resistant. Total flux loss was low and a part was attributed to reversible flux loss, which cannot cause any permanent hysteresis and easily overcome with simple washing. Scanning electron microscopy (SEM) studies were performed for identifying cross sectional morphology. It was pointed out that pore size should be small enough for filtration and optimized for higher flux but pores should be functionalized for rejection. Chemical structure, swelling ratios, sheet resistivity, and fracture morphologies of nanoporous membranes were reported. POLYM. ENG. SCI., 2012. (C) 2012 Society of Plastics Engineers, Scientific and Technological Research Council of TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [108T099], Contract grant sponsor: The Scientific and Technological Research Council of Turkey; contract grant number: 108T099.

This book provides an overall view of the new and highly promising materials and thin film deposition techniques for printable solar cell applications. The book is organized in four parts. Organic and inorganic hybrid materials and solar cell manufacturing techniques are covered in Part I. Part II is devoted to organic materials and processing technologies like spray coating. This part also demonstrates the key features of the interface engineering for the printable organic solar cells. The main focus of the Part III is the perovskite solar cells, which is a new and promising family of the photovoltaic applications. Finally, inorganic materials and solution based thin film formation methods using these materials for printable solar cell application is discussed in Part IV. © 2017 Scrivener Publishing LLC. All rights reserved.

In this study, hydrogen gas generation for Proton Exchange Membrane Fuel Cells (PEMFC) was provided using precious catalysts. The critical catalyst concentration value and the effects of the catalyst amount and the sodium borohydride concentration on the hydrogen production rate were analyzed. PEMFC are one of the good candidates for powering unmanned air vehicles due to their low weight and high durability. They can provide longer flying times than lithium ion batteries. Our group manufactured a PEMFC producing 150 W power for unmanned air vehicles and optimized its performance. Moreover, the influence of the compression and the purge valve on and off time on fuel cell performance was investigated., Int Journal Renewable Energy Res, Comillas Pontif Univ, IEEE, IEEE Power Elect Soc, IEEE Ind Applicat Soc, IBERDROLA, KBSoftware, Asociac Ingenieros ICAI, IEEE Secc Espana, IEEE Spanish Power Elect Ind Elect Joint Chapter, Univ Deusto, iMS, bime, Fraunhofer, INESCTEC, Aalborg Univ, CARTIF, EiC, European Commiss ; Inst Elect Informat ; Commun Engineers Japan, Natl Assoc Spanish ICAI Engineers

Zinc oxide (ZnO) nanostructures were synthesized in the form of nanoparticles, nanoflowers and nanourchins. Structural, electronic and optical characterization of the samples was performed via standard techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence, Raman and ultraviolet-visible (UV-Vis) spectroscopy. Point defect structures which are specific to each morphology have been investigated in terms of their concentration and location via state-of-the-art electron paramagnetic resonance (EPR) spectroscopy. According to the core-shell model, all the samples revealed core defects; however, the defects on the surface are smeared out. Finally, all three morphologies have been tested as electrode materials in a real supercapacitor device and the performance of the device, in particular, the specific capacitance and the storage mechanism, has been mediated by the point defects. Morphology-dependent defective ZnO electrodes enable the monitoring of the working principle of the supercapacitor device ranging from electric double-layer capacitors (EDLC) to pseudo-supercapacitors. © 2020 The Royal Society of Chemistry.

Bu buluş, akışkanların birbirinden bağımsız şekilde anot ve katotta dolaşarak yenilenebilir enerjinin depolanmasını ve depolanan enerjinin kullanılmak üzere sisteme verilmesini sağlayan modüler yapıda silindirik geometriye sahip bir akış bataryası (1) ile ilgilidir.

Introducing a zinc stannate, ZnSnO3 (ZTO), layer on hydrothermally grown 3D-zinc oxide (ZnO) nanosheet thin films has been proven to have a quenching effect on the photoluminescence emissions, indicating very slow recombination of photoinduced electron-hole pairs in photoelectrochemical water splitting (PEC) reactions. Motivated by this, the ZnO/ZTO bilayer system has been used as the electron transport layer for copper indium gallium sulfide (CIGS)-based photoelectrodes in PEC applications. Furthermore, the poor photoresistivity of CIGS has been improved via indium sulfide (In2S3) deposition. Consequently, the photoelectrode obtained from the inverted configuration, ZnO/ZTO/CIGS/In2S3, has generated a photocurrent density of 6.4 mA cm-2 at 0.4 V (vs Ag/AgCl), exceeding the performance of ZnO NS/CIGS/In2S3 photoelectrodes by three folds. The highest ABPE and IPCE efficiencies have been calculated as 4.2% and 57%, respectively. More importantly, two cost-effective nonvacuum techniques for large-scale thin film fabrications such as chemical bath deposition (CBD) and ultrasonic spray pyrolysis (USP) methods have been adopted to acquire photoelectrodes with inverted configurations providing an advantageous approach for low-cost photoelectrode design for sustainable energy production. Copyright © 2020 American Chemical Society.

Poly(acrylonitrile-co-isobutyl methacrylate), PAN-co-PIBMA, and poly(acrylonitrile-co-methyl methacrylate), PAN-co-MMA copolymers are synthesized by emulsion polymerization. The structural characterization is done by FTIR and H-1-NMR spectroscopy and thermal analyses are performed by thermogravimetric analysis (TGA). After various amounts of LiClO4 salt loading into copolymer films, the dielectric properties of these films at different temperatures and frequencies are determined. The effects of different methacrylate groups and salt content on the dielectric properties of copolymers are investigated. It is found that the dielectric constant increases systematically with increasing MMA and IBMA content in the copolymer. The samples with higher salt content show higher ac-conductivities.

Novel polyacrylonitrile (PAN)-co-poly(hydroxyethyl acrylate) (PHEA) copolymers at three different compositions (8,12, and 16 mol % PHEA) and their homopolymers were synthesized systematically by emulsion polymerization. Their chemical structures and compositions were elucidated by Fourier transform infrared, H-1-NMR, and C-13-NMR spectroscopy. Intrinsic viscosity measurements revealed that the molecular weights of the copolymers were quite enough to form ductile films. The influence of the molar fraction of hydroxyethl acrylate on the glass-transition temperature (T-g) and mechanical properties was demonstrated by differential scanning calorimetry and tensile test results, respectively. Additionally, thermogravimetric analysis of copolymers was performed to investigate the degradation mechanism. The swelling behaviors and densities of the free-standing copolymer films were also evaluated. This study showed that one can tailor the hydrogel properties, mechanical properties, and T-g's of copolymers by changing the monomer feed ratios. On the basis of our findings, PAN-co-PHEA copolymer films could be useful for various biomaterial applications requiring good mechanical properties, such as ophthalmic and tissue engineering and also drug and hormone delivery. (C) 2009 Wiley Periodicals, Inc. J AppI Polyrn Sci 116: 628-635, 2010, Contract grant sponsor: Scientific and Technological Research Council of Turkey; contract grant number: 108T099., Scientific and Technological Research Council of TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [108T099]

With this study for the first time effects of post annealing on morphological, structural, optical and electrical properties of spray pyrolyzed copper-indium-gallium-sulfide (CuInGaS2) thin films have been investigated. Pros-and-cons of conventional (CA) and rapid thermal annealing (RTA) have been discussed to obtain the high quality thin film absorbers for solar cell applications. X-ray diffraction analysis revealed that all of the spray pyrolyzed CuInGaS2 thin films have chalcopyrite structures with a highly (112) preferential orientation. Raman spectra also confirmed this structure. However, metal oxide secondary phases such as copper oxide and gallium oxide were detected when the temperature ramp rate was increased during RTA process. Energy dispersive X-ray measurements revealed that both copper and gallium diffused through the surface after annealing processes. Moreover, copper diffusion became pronounced especially at high annealing temperatures. Optical transmission measurements in the wavelength range between 600 and 1100 nm showed that band gap energy of CuInGaS2 thin films was ranging between 1.36 and 1.51 eV depending on the annealing conditions. Very high mobility values have been observed for both processes. The maximum electrical mobility, 30.9 cm(2)/V s, was observed for the films annealed at 600 degrees C via CA. This is the highest reported value among the CuInGaS2 thin film absorbers deposited by both solution and vacuum based techniques. As a result, post-annealing of spray pyrolyzed CuInGaS2 thin films without usage of highly toxic gases, reported in this study, is very promising and environmentally friendly method to produce solar cell quality absorber layers. (C) 2014 Elsevier B.V. All rights reserved., Republic of Turkey Ministry of Science, Industry and TechnologyMinistry of Science, Industry ; Technology - Turkey [01072.STZ.2011-2], This study was supported by Republic of Turkey Ministry of Science, Industry and Technology under the research Grant 01072.STZ.2011-2.

In this study, for the first time, hydrogen gas generation rate is dynamically measured by transferring required amount of sodium borohydride solution to maintain 1 or 2 normal liters of hydrogen gas generation per minute. Three different catalysts (iron, platinum and ruthenium) are used in order to investigate the critical catalyst concentration, catalyst amount and the rate relation and as well as the influence of the sodium borohydride concentration on the rate equations. It has been demonstrated that the linear approximation from the initial hydrogen gas generation data usually reported in the literature is not valid. Moreover, the actual rates reported here are higher and lower than the linear approximations depending on the type of the catalyst. It is about 60 percent lower than linear approximation when iron catalyst is used. Therefore, calculating hydrogen gas generation rate as NL min(-1) g(catalyst)(-1) is invalid. On the other hand, it has been observed that the rate equation may not be dependent on the amount of the sodium borohydride concentration if the highest catalytic activity is achieved. Hence, most of the rate equations in the literature are only valid for a range, which is limited to the highest catalytic activity. Additionally, it has been concluded that the amount of catalyst and sodium borohydride concentration may be optimized to observe almost 100% efficiencies. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved., "The Scientific And Technological Research Council Of Turkey" (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [112M474], Authors would like to appreciate to "The Scientific And Technological Research Council Of Turkey" (TUBITAK) for their support under the contract number 112M474.