Chemistry / Kimya
Permanent URI for this collectionhttps://hdl.handle.net/11147/4072
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Article Citation - WoS: 7Citation - Scopus: 8Investigation 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, EnginStudies 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.Article Citation - WoS: 4Citation - Scopus: 5Mini-Review: "ball-Type Phthalocyanines": Similarities and Differences From Mono Phthalocyanines(Bentham Science Publishers, 2019) Göl, Emre Yusuf; Karabudak, EnginBall-type phthalocyanines are recently synthesized binuclear derivatives of the widely known phthalocyanine molecule. In the ball-type Pc molecule, two cofacially arranged Pc rings have four bridged substituents on the peripheral positions of benzenes. Due to their cofacially arranged phthalocyanine rings and, strong intramolecular and intermolecular interactions, ball-type phthalocyanines have different properties than their parent molecule and these structures have many potential application areas. This review describes three different synthesis methods of ball-type phthalocyanines; synthesis in the solvent, synthesis in solid, and synthesis under microwave irradiation. The synthesis that occurs in the shortest time with the highest yield is the synthesis in the solid phase. General differences between a ball-type phthalocyanine and a monophthalocyanine, such as differences in electronic spectra and effects of cofacial arrangement and central metal atoms, are also discussed. The shape of the Q-bands indicates the differences in electronic spectra. In ball-type Pcs, the Q-bands are broad and have poor resolution. Some potential applications, such as gas sensors, NLO devices, potential usage in photodynamic therapy and artificial photosynthesis of ball-type phthalocyanines are also mentioned. Ball-type Pcs can be used as a sensor for gases such as; CO2, CO, SO2, VOC. A novel water-soluble ball-type Pc may have potential application in PDT. Finally, we consider future prospects of these molecules.Book Part Citation - Scopus: 8The Multiwavelength Uv/Vis Detector: New Possibilities With an Added Spectral Dimension(Springer Verlag, 2016) Karabudak, Engin; Cölfen, HelmutThe multiwavelength (MWL) detector is a new type of absorption detector for AUC. The commercial absorption detector of the Beckman Coulter XLA AUC can only handle a single wavelength per scan with the possibility to scan at maximum 3 wavelengths, whereas MWL-AUC can handle all the wavelengths in the UV/Vis region at one time. The result is impressive since now a full spectral dimension is added to each single scan. In this chapter, we are explaining development history, instrumentation, and future perspective of MWL-AUC.Article Citation - WoS: 12Citation - Scopus: 13History of Spectroscopy and Modern Micromachined Disposable Si Atr-Ir Spectroscopy(Taylor and Francis Ltd., 2018) Koç, Mert; Karabudak, EnginIn this article, the historical development of spectroscopy is examined and the spectroscopy devices used today are described. Then, we focus on infrared (IR) spectroscopy, which cannot give valuable signal in aqueous solution. Attenuated total reflection (ATR)-IR technique solves the problem. In addition, we specifically mention newly developed disposable ATR-IR crystals and micromachined silicon (Si) ATR-IR. Disposable crystal systems and microfluidics systems can be integrated with existing miniature ATR analyzers. If the integration is successful, the technique might be used in biomedical measuring instruments, reactions' analyses, and ultra-high-pressure analyses.Article Citation - WoS: 47Citation - Scopus: 49Simultaneous Identification of Spectral Properties and Sizes of Multiple Particles in Solution With Subnanometer Resolution(John Wiley and Sons Inc., 2016) Karabudak, Engin; Brookes, Emre; Lesnyak, Vladimir; Gaponik, Nikolai; Eychmüller, Alexander; Walter, Johannes; Segets, Doris; Peukert, Wolfgang; Wohlleben, Wendel; Demeler, Borries; Cölfen, HelmutWe report an unsurpassed solution characterization technique based on analytical ultracentrifugation, which demonstrates exceptional potential for resolving particle sizes in solution with sub-nm resolution. We achieve this improvement in resolution by simultaneously measuring UV/Vis spectra while hydrodynamically separating individual components in the mixture. By equipping an analytical ultracentrifuge with a novel multi-wavelength detector, we are adding a new spectral discovery dimension to traditional hydrodynamic characterization, and amplify the information obtained by orders of magnitude. We demonstrate the power of this technique by characterizing unpurified CdTe nanoparticle samples, avoiding tedious and often impossible purification and fractionation of nanoparticles into apparently monodisperse fractions. With this approach, we have for the first time identified the pure spectral properties and band-gap positions of discrete species present in the CdTe mixture.