Yazar "Ermis, Ismail" seçeneğine göre listele

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    Direct-methanol Fuel Cell Based on Functionalized Graphene Oxide with Mono-metallic and Bi-metallic Nanoparticles: Electrochemical Performances of Nanomaterials for Methanol Oxidation
    (Wiley-V C H Verlag Gmbh, 2016) Yola, Mehmet Lutfi; Eren, Tanju; Atar, Necip; Saral, Hasan; Ermis, Ismail
    The catalysts based on 2-aminoethanethiol functionalized graphene oxide (AETGO) with several mono-metallic and bi-metallic nanoparticles such as rod gold (rAuNPs), rod silver (rAgNPs), rod gold-platinum (rAu-Pt NPs) and rod silver-platinum (rAg-Pt NPs) were synthesized. The successful synthesis of nanomaterials was confirmed by various methods. The effective surface area (ESA) of the rAu-Pt NPs/AETGO is 1.44, 1.64 and 2.40 times higher than those of rAg-Pt NPs/AETGO, rAuNPs/AETGO and rAgNPs/AETGO, respectively, under the same amount of Pt. The rAu-Pt NPs/AETGO exhibited a higher peak current for methanol oxidation than those of comparable rAg-Pt NPs/AETGO under the same amount of Pt loading.
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    Electrical properties of triple-doped bismuth oxide electrolyte for solid oxide fuel cells
    (Taylor & Francis Ltd, 2016) Gonen, Yunus Emre; Ermis, Ismail; Ari, Mehmet
    In this study, the quaternary solid solutions of (Bi2O3)((0.8-x))(Tb4O7)(0.1)(Ho2O3)(0.1)(Dy2O3)(x) (x = 0.05, 0.10, 0.15, 0.20) as an electrolyte were synthesized for solid oxide fuel cells by the technique of solid-state synthesis. The products were characterized by X-ray powder diffraction, differential thermal analysis/thermal gravimetry and the four-point probe technique (4PPT). The total electrical conductivity is measured on the temperature and the doped concentration by 4PPT. All samples have been obtained as the delta-phase. According to the measurements of the 4PPT, the electrical conductivities of the samples increase with the temperature but decrease with the amount of doping rate. The value of the highest conductivity (sigma) is found as 1.02 x 10(-1) S cm(-1) for the system of (Bi2O3)(0.75)(Tb4O7)(0.1)(Ho2O3)(0.1)(Dy2O3)(0.05) at 850 degrees C. The thermal gravimetry (TG) curve shows that there is no mass loss of sample during the measurement. The analyses of differential thermal reveal that there are neither endothermic peaks nor exothermic peaks during the heating and cooling cycles (ranging from 30 to 1000 degrees C).
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    Fabrication of Bi0.95-xEr0.05MxO1.5-δ (M = Lu, Ho, and Gd) electrolyte for intermediate temperature solid oxide fuel cells
    (Springer, 2019) Ermis, Ismail
    In this study, the samples of Lu2O3, Gd2O3, and Ho2O3 are firstly chosen as co-dopants with Er2O3 in order to stabilize delta phase Bi2O3 ceramics. The effects of co-dopants were investigated on phase stability and electrical conductivity of Bi0.95-xEr0.05MxO1.5-delta (M = Lu, Gd, and Ho) with x = 0.05 and 0.1 M ratio concentrations. The phase structure of samples was determined by X-ray diffraction method, the features of surface morphology are shown by scanning electron microscope, and the electrical conductivity is measured by AC impedance spectroscopy. All the samples have a face-centered cubic structure (fcc) at a lower sintering temperature (850 degrees C). The unit cell parameters are reduced due to the smaller dopant cations than Bi3+. The change of electrical conductivity in terms of the ionic radii, amount of doping, and temperature of the samples was investigated. The electrical conductivity increases with the radius of the doping ions. However, the increased amount of doping reduces conductivity. At the same time, the electrical conductivity of all the samples has increased with temperature. The best conductivity values are 0.489, 0.341, and 0.258 Scm(-1) at 800, 700, and 600 degrees C, respectively for Bi0.90Er0.05Gd0.05O1.5. These values are significantly higher than the values found in the literature.
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    Phase stability and electric conductivity of Eu2O3-Tb4O7 co-doped Bi2O3 electrolyte
    (Pergamon-Elsevier Science Ltd, 2015) Ermis, Ismail; Ari, Mehmet; Acer, Semra Durmus; Dagdemir, Yilmaz
    In this study, eight different samples of Tb4O7 and Eu2O3 co-doped Bi2O3 were prepared by solid-state synthesis techniques. (Bi2O3)(1-x-y)(Tb4O7)(x)(Eu2O3)(y) (x = 5,10; y = 5, 10, 15, 20 mol %) ternary systems were investigated by using X-ray powder diffraction (XRD), differential thermal analysis/thermal gravimetry (DTA/TG), and four-point probe techniques (4PPT). Effect of concentration of doping elements on the temperature and electrical conductivity was investigated. All samples were evaluated by calculating activation energies and average crystal sizes. XRD measurements show that five samples have a single phase (phase) structure. According to electrical conductivity measurements, the conductivity increases with increasing temperature but decreases with increasing amount of Eu2O3. The highest ionic conductivity was measured as 7.28 x 10(-1) (ohm.cm)(-1) for the (Bi2O3)(0.90)(Tb4O7)(0.05) (Eu2O3)(0.05) sample at 850 degrees C and the lowest activation energy was measured as 0.64 eV for (Bi2O3)(0.90)(Tb4O7)(0.05) (Eu2O3)(0.05). Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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    Platinum nanoparticles supported on nitrogen and sulfur-doped reduced graphene oxide nanomaterial as highly active electrocatalysts for methanol oxidation
    (Springer, 2016) Akyildirim, Onur; Yuksek, Haydar; Saral, Hasan; Ermis, Ismail; Eren, Tanju; Yola, Mehmet Lutfi
    A fuel cell is an electrochemical cell that converts a source fuel into an electrical current. It generates electricity inside a cell through reactions between a fuel and an oxidant, triggered in the presence of an electrolyte. Fuel cells have been attracting more and more attention in recent decades due to high-energy demands, fossil fuel depletions and environmental pollution throughout world. In this study, a facile and cost-effective catalysts have been developed on platinum nanoparticles (PtNPs) supported on nitrogen and sulfur-doped reduced graphene oxide (NSrGO). The successful synthesis of nanomaterials and the prepared glassy carbon electrode (GCE) surfaces were confirmed by transmission electron microscope (TEM), X-ray photo electron spectroscopy (XPS), scanning electron microscope (SEM) and electrochemical impedance spectroscopy (EIS). According to TEM images, the average particle sizes of PtNPs were found to be approximately 15-20 nm. The effective surface areas (ESA) of NSrGO/GCE and PtNPs/NSrGO/GCE were calculated to be 148 and 469 cm(2)/mg, respectively. The PtNPs/NSrGO/GCE also exhibited a higher peak current for methanol oxidation than those of comparable GCE and NSrGO/GCE, providing evidence for its higher electro-catalytic activity.
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    Sensitive analysis of simazine based on platinum nanoparticles on polyoxometalate/multi-walled carbon nanotubes
    (Academic Press Inc Elsevier Science, 2016) Ertan, Bengue; Eren, Tanju; Ermis, Ismail; Saral, Hasan; Atar, Necip; Yola, Mehmet Lutfi
    In this report, a novel molecular imprinted voltammetric sensor based on glassy carbon electrode (GCE) modified with platinum nanoparticles (PtNPs) involved in a polyoxometalate (H3PW12O40, POM) functionalized multi -walled carbon nanotubes (MWCNs) sheets was prepared for the determination of simazine (SIM). The developed surfaces were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) method. SIM imprinted GCE was prepared via electropolymerization process of 100 mM pyrrole as monomer in the presence of 0.1 M acetate buffer (pH 4.0) containing 25 mM SIM. The linearity range and the detection limit of the developed method were calculated as 1.0 x 10(-19)-5.0 x 10(-9) M and 2.0 x 10(-11) M, respectively. In addition, the voltammetric sensor was applied to wastewater samples. The stability and reproducibility of the voltammetric sensor were also reported. (C) 2016 Elsevier Inc. All rights reserved.
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    Study of crystallographic, thermal and electrical properties of (Bi2O3)1-x-y(Tb4O7)x(Gd2O3)y electrolyte for SOFC application
    (Elsevier Sci Ltd, 2018) Ermis, Ismail; Shaikh, S. P. S.
    In this study, (Bi2O3)(1-x-y)(Tb4O7)(x)(Gd2O3)(y) (xTbyGdSBi) ternary solid solutions were synthesized via the solidstate synthesis technique. The phase structures of electrolytes were defined by X-ray powder diffraction (XRD) and differential thermal analysis/thermal gravimetric techniques (DTA/TG). The total electrical conductivity (sigma(T)) was measured with respect to the test temperature and doping concentration by using four-point probe technique (4PPT). Measurement results showed that 8-phase was obtained in test specimens and the conductivity of the electrolytes increased with increasing test temperature and decreasing amount of Gd203. The 5Tb5GdSBi ternary system had the highest conductivity value of 3.88 x 10(-1) S cm(-1) at 850 degrees C. Compared to the literature, the results from this study are reasonably promising.
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    Synthesis of (Bi2O3)0.9-x(Tb4O7)0.1(Sm2O3)x electrolyte for IT-SOFCs
    (Taylor & Francis Inc, 2018) Ermis, Ismail; Sertkol, Murat; Corumlu, Vahit; Dagdemir, Yilmaz; Ari, Mehmet
    In this study (Bi2O3)(0.9-x)(Tb4O7)(0.1)(Sm2O3)(x) ternary solid solutions were synthesized by solid-state synthesis techniques. The products were characterized by means of X-ray powder diffraction, differential thermal analysis/thermal gravimetry, and the four-point probe technique (4PPT). Total electrical conductivity (sigma T) depending on the temperature and doping concentration has been measured by 4PPT. Activation energy of the four samples are calculated by Arrhenius relation. Activation energies of the samples increases with the concentration of dopant Sm2O3. Bi2O3-based ceramic system doped with Sm2O3 and Tb4O7 showed an oxide ionic-type electrical conductivity which is increased with the increasing amount of Sm2O3. The highest conductivity value is found as 3.48x10(-1) S cm(-1) for the (Bi2O3)(0.85)(Tb4O7)(0.1)(Sm2O3)(0.05) ternary system at 850 degrees C.
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    The phase stability and conductivity of Ho2O3-Gd2O3 co-doped electrolyte for solid oxide fuel cell
    (Springer, 2016) Corumlu, Vahit; Ermis, Ismail; Acer, Semra D.; Cifci, Tugba; Dagdemir, Yilmaz; Ari, Mehmet
    In this study, Bi2O3 ternary system sample materials were synthesized by using solid state reaction method. Two oxides, Ho2O3 and Gd2O3, were used to stabilize the delta (cubic) Bi2O3 phase used as an electrolyte of solid oxide fuel cell applications. The characteristics and electrical properties of these electrolyte samples for solid oxide fuel cells were evaluated by X-ray diffraction (XRD), scanning electron microscope and the four-point probe technique. According to XRD measurements, delta-phase (x = 0.05-0.1, y = 0.05, 0.1, 0.15, 0.2) samples were obtained with a stable structure. The results of the electrical measurements of the (Bi2O3)(1-x-y)(Ho2O3)(x) (Gd2O3) y ternary system show that the electrical conductivity increase with decreasing amount of Gd2O3 molar ratio at a fixed molar ratio of Ho2O3. The value of highest conductivity was found as 2.53 x 10(-1) S cm(-1) for the (Bi2O3)(1-x-y)(Ho2O3)(x)(Gd2O32O3)(y) ternary system (x = 0.05 mol% and y = 0.05 mol%) at 973 K. It was found that activation energy at low temperature varied from 1.10 to 1.29 eV and the activation energy at high temperature varied from 0.61 to 0.70 eV.