Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 10Citation - Scopus: 12Li-Ion Battery Cathode Performance From the Electrospun Binary Licoo2 To Ternary Li2coti3o8(Springer Verlag, 2020) Kap, Özlem; İnan, Alper; Er, Mesut; Horzum, NesrinMetal oxide nanofibers are prepared by electrospinning and are developed to be the electrodes for lithium-ion batteries (LIBs). The effect of calcination temperature and the Li:Co mole ratio of LiCoO2 nanofibers was investigated on the electrochemical cathode performance in a coin cell battery. The higher temperature calcination and Li:Co mole ratio have improved the electrochemical performance of the nanofibers. Lithium cobalt oxide (LiCoO2) nanofibers obtained at 400 and 700 degrees C retain 65% and 90% of the initial capacity, respectively, after the high-current test and the C-rate reverted to 0.1 C. When doubling the mole ratio of Li:Co (2:1), an increase in specific capacity values from 78 to 148 mAh g(-1) has been provided. Additionally, colloidal titania nanoparticles (TiO2 NPs)-doped LiCoO2 nanofibers were obtained and investigated as a cathode material. While the increment in calcination temperature results in higher crystallinity and stability of the LiCoO2 phase, in the presence of the TiO2 NPs causes a transformation of binary (LiCoO2/TiO2) to ternary Li-based transition metal oxide (Li2CoTi3O8/TiO2). An initial discharge capacity of 82 mAh g(-1) was found at 0.1 C for the Li2CoTi3O8/TiO2 nanoparticles and the capacity retention was 83% when returned to 0.1 C after 25 cycles.Article Citation - WoS: 11Citation - Scopus: 11Structural Stability of Physisorbed Air-Oxidized Decanethiols on Au(111)(American Chemical Society, 2020) Kabanoy, Nikolai; Tsvetanova, Martina; Klaysyuk, Andrey L.; Zandvliet, Harold J. W.; Sotthewes, Kai; Kap, Özlem; Varlıklı, CananWe have studied the dynamic behavior of decanethiol and air-oxidized decanethiol self-assembled monolayers (SAMs) on Au(111) using time-resolved scanning tunneling microscopy at room temperature. The air-oxidized decanethiols arrange in a lamellae-like structure leaving the herringbone reconstruction of the Au(111) surface intact, indicating a rather weak interaction between the molecules and the surface. Successive STM images show that the air-oxidized molecules are structurally more stable as compared to the nonoxidized decanethiol molecules. This is further confirmed by performing current-time traces with the feedback loop disabled at different locations and at different molecular phases. Density function theory calculations reveal that the diffusion barrier of the physisorbed oxidized decanethiol molecule on Au(111) is about 100 meV higher than the diffusion barrier of a chemisorbed Au-decanethiol complex on Au(111). A two-dimensional activity map of individual current-time traces performed on the air-oxidized decanethiol phase reveals that all the dynamic events take place within the vacancy lines between the air-oxidized decanethiols. These results reveal that the oxidation of thiols provides a pathway to produce more robust and stable self-assembled monolayers at ambient conditions.Article Citation - WoS: 12Citation - Scopus: 12Ordering of Air-Oxidized Decanethiols on Au(111)(American Chemical Society, 2018) Sotthewes, Kai; Kap, Özlem; Wu, Hairong; Thompson, Damien; Huskens, Jurriaan; Zandvliet, Harold J. W.Self-assembled monolayers (SAMs) of alkanethiols on gold are a commonly used platform for nanotechnology owing to their ease of preparation and high surface coverage. Unfortunately, the gold-sulfur bond is oxidized at ambient conditions which alters the stability and structure of the monolayer. We show using scanning tunneling microscopy and X-ray photoelectron spectroscopy that decanethiolate molecules oxidize into decanesulfonates that organize into a hitherto unknown striped phase. Air-exposed SAMs oxidize, as can be determined by a shift of the S 2p peak and the appearance of O 1s photoelectrons as part of the decanethiol monolayer transforms into a lamellae-like decanesulfonate structure when exposed to air. The herringbone structure of the Au(111) surface is preserved, indicating that the interaction between the molecules and the surface is rather weak as these findings are substantiated by density functional theory calculations.