Tez Türü: Yüksek Lisans
Tezin Yürütüldüğü Kurum: Yıldız Teknik Üniversitesi, Kimya-Metalurji Fakültesi, Met.Ve Malzeme Müh.Böl., Türkiye
Tez Danışmanı: Metin Gençten
Tezin Onay Tarihi: 2026
Tezin Dili: İngilizce
Özet:
Increased environmental damage caused by fossil fuel consumption has stimulated significant research into alternative and more environmentally friendly energy storage systems. Among these, supercapacitors attract great interest due to their high power densities and specific capacitances. The choice of electrode material plays a critical role in determining the electrochemical performance of supercapacitors. Commonly used electrode materials include carbon-based materials, conducting polymers, and various metal oxides. Among metal oxides, ruthenium oxide exhibits superior electrochemical properties; however, its high cost and the toxicity associated with its production limit its widespread use. In this context, cobalt-based materials, particularly cobalt oxide and cobalt hydroxide, stand out as promising alternatives thanks to their specific capacitance values comparable to those of ruthenium oxide. In this study, to address the aforementioned limitation, cobalt oxide (Co2O3, sample ST3) and cobalt oxyhydroxide ("CoOOH" , sample SC3) materials with nanoflower-like morphology were synthesized via the cyclic voltammetry method using cobalt nitrate as the starting material. Comprehensive characterization studies were performed via XRD, SEM, XPS, and BET analyses to confirm the morphological and structural properties of the synthesized materials. Additionally, the electrochemical performance was evaluated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD) tests. Following the tests, superior performance was demonstrated. At a scan rate of 5" mV/s" , the specific capacitance values of "CoOOH" and 〖"Co" 〗_2 "O" _3 were found to be 99.5 and 112 mF/cm2, respectively. Furthermore, after 10,000 charge-discharge cycles at a charge-discharge current density of 3mA.cm-2, the capacity retention values were realized as %84,24 and %85,50 for "CoOOH" and for 〖"Co" 〗_2 "O" _3. Due to the high capacity and specific capacitance they exhibit throughout the extended cycle tests, cobalt oxide materials with nanoflower-like structures are considered strong candidates for next-generation supercapacitors.