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Öğe A novel H2S/H2O2 fuel cell operating at the temperature of 298K(Wiley, 2013) Sanli, Ayse Elif; Yilmaz, Orhan; Aytac, AylinIn this study, the oxidation mechanism of hydrogen sulfide (H2S) is investigated, and a fuel cell operating with acidic peroxide as oxidant and basic hydrogen sulfide as fuel is constructed. A stable solid state H2S/H2O2 fuel cell has been developed at the temperature of 298K. A nickel anode catalyst has been examined using Nafion-117 as a proton-conducting membrane. In an operating with the acidic hydrogen peroxide (H2O2) as oxidant, the cell potential was increased to a value of 0.85V at 298K. The main conclusion of this study is the management to increase the cell potential to 850mV at 25 degrees C, whereas this value can only be achieved in the H2S/O-2 fuel cell at 850-1000 degrees C. Moreover, there exists no prior work on the H2S/H2O2 fuel cell research. Copyright (c) 2012 John Wiley & Sons, Ltd.Öğe Deniz suyundaki hidrojen sülfürün ($H_2S$) farklı metal elektrotlar kullanılarak elektro-oksidasyonunun incelenmesi(2013) SANLI, Ayşe Elif; Aytac, AylinHidrojen sülfür (H2S) önemli bir hidrojen kaynağıdır. H2S’den elektroliz ile hidrojen veya elektrooxidasyon ile doğrudan elektrik enerjisi elde edilmektedir. Bu çalışmada Karadeniz suyunda yüksek miktarda bulunan H2S’ün yakıt pillerinde doğrudan elektrik enerjisine dönüştürülmesi incelenmiştir. Nikel ve kobalt elektrotların elektrokimyasal testleri sonucunda Nikel’in uygun bir katalizör olduğu anlaşılmıştır. Nikel anot ile hazırlanan bir yakıt pilinde, bazik Na2S+yapay deniz suyu çözeltisi kullanılarak, oda sıcaklığında 9.2 mW/cm2 güç yoğunluğuna ulaşılmıştır.Öğe Development of a power management unit for small portable direct borohydride fuel cell-NiMH battery hybrid system(Pergamon-Elsevier Science Ltd, 2012) Sanli, Ayse Elif; Gunlu, Goksel; Aytac, Aylin; Mat, MahmutIn this study, a small portable fuel cell/battery hybrid system has been developed. The system consists of a single portable direct borohydride/peroxide fuel cell (DBPFC), NiMH battery and power management unit (PMU). The battery has been used as a primary power source and has been discharged at constant load. When its state of charge is reduced, the DBPFC charges the battery and powers the load simultaneously. A DC-DC Boost converter has been used as a PMU. The DBPFC has provided the total power of 0.21 Wh into the system during the charge. During this experimental study fuel (NaBH4) efficiency of 37% has been achieved in the hybrid system, while the system efficiency has been calculated as 34.5%. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Öğe Electrochemistry of The Nickel Electrode as a Cathode Catalyst In The Media Of Acidic Peroxide For Application of The Peroxide Fuel Cell(Electrochemical Soc Inc, 2012) Sanli, Ayse Elif; Aytac, AylinHydrogen peroxide reduces on the nickel electrode surface in the acidic medium. On the nickel electrode the passive film layers such as NiS and NiOOH form in the peroxide free solution. However the nickel surface was activated with the addition of the peroxide. The cyclic voltammetry (CV) and impedance (EIS) studies verified the passivation and activation states in peroxide free acidic solution and the acidic peroxide solution. The electrochemical reactions of the sulphuric acid and peroxide at nickel electrode were electrochemically analyzed by cyclic voltammetry (CV) and impedance spectroscopy (EIS)Öğe Electrooxidation of hydrogen peroxide and sodium borohydride on Ni deposited carbon fiber electrode for alkaline fuel cells(Pergamon-Elsevier Science Ltd, 2011) Aytac, Aylin; Gurbuz, Mehmet; Sanli, A. ElifIn this study, Ni deposited carbon fiber electrode (Ni/CF) prepared by electroless deposition method was examined for their redox process and electrocatalytic activities during the oxidation of hydrogen peroxide and sodium borohydride in alkaline solutions. The Ni/CF catalyst was characterized by X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM) and electrochemical voltammetry analysis. The electrocatalytic activity of the Ni/CF for oxidation of hydrogen peroxide and sodium borohydride in alkaline solutions was investigated by cyclic voltammetry. The anodic peak current density is found to be three times higher on Ni/CF catalyst for sodium borohydride compared to that for hydrogen peroxide. Preliminary tests on a single cell of a direct borohydride/peroxide fuel cell (DBPFC) and direct peroxide/peroxide fuel cell (DPPFC) indicate that DBPFC with the power density of 5.9 mW cm(-2) provides higher performance than DPPFC (3.8 mWcm(-2)). Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Öğe Investigation of the electro-oxidation of artificial Black Sea water by cyclic voltammetry on molybdenum (II)(Pergamon-Elsevier Science Ltd, 2014) Sanli, Ayse Elif; Aytac, Aylin; Mat, MahmutThe electro-oxidation of H2S in Black Sea water to generate electricity was investigated. MoS2 exhibited catalytic activity toward the oxidation of H2S in artificial sea water. The catalytic activity of molybdenum sulfide was found to depend on the electrolyte pH and on the temperature. Cyclic voltammograms taken in the artificial sea water containing hydrogen sulfide at pH = 14 exhibited a peak at 500 mV related to the oxidation of HS-. Furthermore, the peak current of the MoS2 electrode increased to 400 mA g(-1) from 250 mA g(-1) (approximately 1.6-fold) when the temperature was increased from 353 K to 363 K. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Öğe Investigation of the electro-oxidation of artificial Black Sea water using cyclic voltammetry on metal sulfide electrodes (I)(Pergamon-Elsevier Science Ltd, 2014) Sanli, Ayse Elif; Yilmaz, Orhan; Aytac, Aylin; Mat, Mahmut D.Black Seawater is an alternative hydrogen source because it has hydrogen sulfide content. Seawater electrolysis is a promising method to produce hydrogen. The anodic oxidation of hydrogen sulfide is a novel approach for directly generating electricity via fuel cells. Therefore, four materials (Cu, Stainless Steel 304 (SS), V2O5 and Ni) were examined in artificial seawater containing hydrogen sulfide (HS-). We developed active metal sulfide electrodes for oxidizing HS-. Alongside the corrosion potentials, the progression of the oxidation and reduction reactions was obtained by the cyclic voltammetry method. The active behaviors of the metal sulfide (MSx) layers were determined by applying Electrochemical Impedance Spectroscopy (EIS). Although the Cu2S electrode acts as the active catalyst during HS- ion oxidation, NiS is the most suitable metal sulfide because it exhibits a higher corrosion resistance than Cu2S. While V2O5 demonstrates catalytic activity at high temperatures (>= 30 degrees C), FeS layers corrode easily in the artificial seawater environment. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Öğe Use of the Blacksea Water Containing Hydrogen Sulfide (H2s) as a Fuel Cell Fuel(Electrochemical Soc Inc, 2015) Sanli, Ayse Elif; Canan, Belkis; Aytac, AylinBlack Seawater is a hydrogen source because of high hydrogen sulfide (H2S) content. H2S is the chemical electron donor. Energy can be generated from H2S by the oxidation or by the electrooxidation. Electrochemical systems such as fuel cells are the powerful alternative to recovery of sulfur and to generate energy. In the present study Black seawater with H2S content has been investigated as a fuel cell fuel. The electrochemical behaviors of metal sulfides have been performed in the solution containing H2S. NiS has showed the catalytic effect towards the electro- oxidation of HS- ions. A fuel cell constructed with Ni anode and Pt cathode has provided the maximum power density of 23 mWcm(-2) at the potential of 300 mV and 75 mAcm(-2).
