Browsing by Author "Aytekin, Ahmet"

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Citation - WoS: 6
Citation - Scopus: 7
Investigation of Oxygen Evolution Reaction Performance of Silver Doped Ba0.5sr0.5co0.8fe0.2o3-Delta Perovskite Structure
(Springer, 2020) Göl, Emre Yusuf; Aytekin, Ahmet; Özkahraman, Ecem Ezgi; Karabudak, Engin; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
Studies on novel electrochemical catalyst synthesis for efficient oxygen evolution reaction (OER) attract the attention of researchers. In general, changing of synthesis method and the doping metal affect the electrochemical activities of BSCF. In this work, silver doped Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF-Ag) perovskite structure is shown to be a better electrocatalyst for oxygen evolution reaction (OER) due to its lower overpotential and extended durability. BSCF structure was synthesized by the EDTA-citric acid method. Appropriate amount of Ba(NO3)(2) and EDTA were dissolved 0.1 M NH4OH solution. Nitrate salts of other metals were dissolved in distilled water, then mixed with prepared Ba(NO3)(2) solution. The mixture was stirred at 70 degrees C until gelation occurred. The gelled samples obtained were baked in a drying oven at 250 degrees C for 24 h before being calcined at 1000 degrees C for 12 h. To achieve a current density of 10 mA cm(-2), BSCF-Ag has required an overpotential of 0.36 V, which is very low compared to BSCF. To determine the stability of BSCF-Ag, continuous chronopotentiometry tests were carried out for 5 h and at a constant current density of 10 mA cm(-2). BSCF-Ag was characterized by XRD, SEM, and XPS.
Investigation of the Experimental and Theoretical Band Gap of Pbvo3cl for Use in Energy Conversion Devices
(Pergamon-elsevier Science Ltd, 2024) Harmanli, Ipek; Aytekin, Ahmet; Gol, Emre Yusuf; Eanes, Mehtap; Karabudak, Engin; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
The major goal of the research described in this paper is to investigate the structure of electronic band and band gap of the novel semiconductor lead (II) trioxovanadate (V) chloride (PbVO3Cl). 3 Cl). Depending on both experimental and theoretical (computational) results, the utility of PbVO3Cl 3 Cl as a semiconductor in solar fuel devices was discussed. The optical band gap was determined experimentally by applying Tauc Plot method to the absorption spectra of PbVO3Cl. 3 Cl. Additionally, computational approaches for the structure prediction of PbVO3Cl 3 Cl have been studied. The electronic band structures were examined theoretically using local density (LDA), generalized gradient (GGA), and hybrid (HSE06) approximations. PbVO3Cl, 3 Cl, which has an optical band gap of about 2.2 eV, has been shown to have promising photocatalytic properties. As a result of these approximations, the transition type of PbVO3Cl 3 Cl was determined as indirect. We also discussed the potential future application of PbVO3Cl 3 Cl in Lewis solar fuel devices as a combination of the photoanode and Si photocathode. And the solar efficiency of the PbVO3Cl-Si 3 Cl-Si double-layer semiconductor system was calculated. Further experimental proofs can be important.
Citation - Scopus: 1
Investigation on the Keggin Anchored on Hydroxide-Functionalized Single-Walled Carbon Nanotubes as Superior Cathode for Aqueous Zinc-Ion Batteries
(American Chemical Society, 2025) Chilufya, Langson; Sertbaş, Vahide; Aytekin, Ahmet; Karabudak, Engin; Emirdag-Eanes, Mehtap; 01. Izmir Institute of Technology; 04. Faculty of Science; 04.01. Department of Chemistry
Rechargeable aqueous zinc-ion batteries (AZIBs) have become a viable option in electrochemical energy storage systems (EESS) owing to their inherent safety features and economic friendliness. Nonetheless, creating suitable cathode materials for AZIBs with high structural stability, good rate performance, and great capacity remains a significant challenge. Polyoxometalate (POM)-based nanohybrid materials have shown promising results in high cycling stability and great specific capacity. However, POMs susceptible to electrolyte dissolution and the sluggish Zn-ion (Zn2+) kinetics have significantly hampered their electrochemical performance as cathodes for AZIBs. Herein, we present a Keggin POM, K3[PW12O40]·nH2O (KPW12), anchored on hydroxyl (OH)-functionalized single-walled carbon nanotubes (SWOH) that were fabricated via a facile ultrasonication procedure. Employed as cathodes for AZIBs, the optimal KPW12/SWOH feature exhibited remarkable electrochemical performance. The system satisfied the Zn2+storage, achieving a reversible discharge capacity of 183 mAh g–1at a high current density of 5C with a flat and long discharge plateau after 160 cycles. The perfect synergistic contribution of the pseudocapacitive nature of the super-reduced state of KPW12and the electron-conductive network of SWOH was attributed to this exceptional electrochemical performance. Furthermore, the presence of oxygen in SWOH enhanced the transfer kinetics of electrons and smooth Zn2+diffusion while lowering the Zn2+migration energy barrier by providing more accessible active sites. This demonstrates remarkable promise in fabricating robust electrode materials optimized for integration within aqueous battery systems that pave the way for further research into POM-based materials for EESS. © 2025 Elsevier B.V., All rights reserved.
Synthesis, Characterization, Optimization, and Electrochemical Analysis of Novel Multimetal Oxide Materials for Energy Applications
(01. Izmir Institute of Technology, 2024) Karabudak, Engin; Aytekin, Ahmet; Karabudak, Engin; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
Son zamanlarda, enerji ve enerjiye olan ihtiyaç gittikçe artmaktadır. Bu enerji ihtayacını karşılamak adına, araştırmacılar enerji ile ilintili malzemelerin elektrokimyasal özelliklerini ve kullanım alanlarını iyileştirmek için çalışmaktadırlar. Günümüzde, multimetal oksit malzemeler bataryada (lityum iyon batarya ve Ni tabanlı batarya), yarı iletkenlerde, suyu ayrıştırma çalışmalarında, yakıt hücrelerinde ve kataliz çalışmalarında geniş bir şekilde kullanılmaktadır. Bu tezde nikel hidroksit (alfa ve beta formu), üre parçalanması metoduyla sentezlenmiştir. Kobalt, çinko, alüminyum ve bakır katkılı Ni(OH)2 aynı metotla sentezlenmiştir. Bu katkılı nikel hidroksitlerin elektrokimyasal analizi yapılmış ve karakterize edilmiştir. Nikel hidroksit kapasitesini iyileştirmek için küçük bir hücre çalışması yapılmış ve optimizasyon çalışması yapılarak bazı etkiler (c rate, tutkal etkisi ve elektrolit etki) incelenmiştir. Ayrıca NMC katot malzemesi katı-hal yöntemi ile sentezlenmiş ve kapasite çalışması yapılmıştır. Çalışmada BSCF, Ag-BSCF ve yeni BSNF malzemeleri sol jel yöntemi ile sentezlenmiş ve karakterize edilmiştir. Ayrıca, perovskite sınıfında olup olmadıklarını belirlemek adına Goldschmidt tolerans faktörleri hesaplanmış ve tartışılmıştır. Tezde çeşitli metal tuzları (Cr, Co, Fe, Mn, Ni) kullanılarak basılabilir mürekkep hazırlanmıştır. Hazırlanmış olan basılabilir mürekkeplerin optimizasyon çalışması yapılmıştır. Bu mürekkeplerden yola çıkarak multimetal oksit katalizörleri sentezlenmiştir, bu da suyu ayrıştırarak hidrojen ve oksijen elde etme imkanı sunar. Son olarak, PbVO3CI malzemesi sentezlenmiş ve karakterize edilmiştir. Yarı iletkenliği, elektronik yapısı, dinamik kararlılığı (Born-Phonon) ve perovskite sınıfı özelliği ele alınmıştır. Tezde, irdelenen bu malzemeler ( özellikle Ag-BSCF, BSNF, PbVO3CI) solar hücrelerde, katı hal yakıt hücrelerinde (SOFC), bataryalarda, yarı iletken ve katalizör çalışmalarında kullanılabilme potansiyeline sahiptir.