Date of Award
Master of Science (MS)
Dr. Ram Gupta, firstname.lastname@example.org
Dr. Khamis Siam, email@example.com
Dr. Pawan Kahol, firstname.lastname@example.org
Dr. John Franklin, email@example.com
Metal oxides are being used for various applications, such as batteries, supercapacitors, and catalysts. This research is mainly to produce high-performance energy storage devices capable of working at high temperatures and causing no pollution in the environment. To this end, the effect of metal ion substitution on the electrochemical properties of Co3O4 for energy applications was studied. Different metal oxides, such as FeCo2O4, MnCo2O4, Co3O4, NiCo2O4, CuCo2O4, and ZnCo2O4, were synthesized using a hydrothermal process. These metal oxides were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), confirming the formation of phase pure materials. The electrochemical properties were studied using cyclic voltammetry (CV), galvanostatic charge-discharge techniques, and electrochemical impedance spectroscopy where it was observed that electrochemical properties of the metal oxides depend on their composition. A maximum specific capacitance of 1319 F/g at 1 mV/s was observed for FeCo2O4. Additionally, the specific capacitance of a supercapacitor device fabricated using tow FeCo2O4 electrodes were observed to decrease with an increase in scans rate and current density. The effect of temperature on energy storage capacity of the device was also investigated, and an improvement in energy storage capacity was observed with an increase in temperature, which resulted in an over 100% improvement in charge storage capacity of the supercapacitor device on increasing temperature from 10 to 70 oC. It was found that FeCo2 O4 also acts as an efficient electrocatalyst for oxygen evolution reaction (OER). FeCo2 O4 showed the lowest overpotential of 308 mV with the resistance of 3.4 ohm, which was the lowest overpotential among other studied metal oxides. This work demonstrates that electrochemical properties of metal oxides can be tuned by proper metal ion substitution and could be used as advanced materials for supercapacitors and as electrocatalysts.
Alqahtani, Dalal, "Effect of Metal Ion Substitution on Electrochemical Properties of Cobalt Oxide for Energy Applications" (2017). Electronic Theses & Dissertations. 258.