NANOCOMPOSITES OF POLYPYRROLE AND COBALT OXIDE AS EFFICIENT AND STABLE MULTIFUNCTIONAL MATERIALS FOR SUPERCAPACITORS AND OVERALL WATER SPLITTING

NANOCOMPOSITES OF POLYPYRROLE AND COBALT OXIDE AS EFFICIENT AND STABLE MULTIFUNCTIONAL MATERIALS FOR SUPERCAPACITORS AND OVERALL WATER SPLITTING An Abstract of the Thesis by Ahlam Alghamdi The main objective of this study is to synthesize nanostructured cobalt oxide decorated on polypyrrole using a facile method for energy applications. For this, polypyrrole was first synthesized using a chemical polymerization method. In the second step, a varying amount of cobalt oxide was decorated on polypyrrole using a hydrothermal process. The synthesized materials were structurally and electrochemically characterized. It was observed that the electrochemical properties of the composites depend on their composition. The optimized composition showed a maximum specific capacitance of 1533 F/g at 1 mV/s with a significant electrochemical stability. The composite retained ~87% of its initial charge storage capacity even after 5,000 cycles of charging-discharging studies. Moreover, these composites showed outstanding performance as an electrocatalyst for oxygen and hydrogen evolution reactions. It required an overpotential of 316 mV and 132 mV to achieve a current density of 10 mA/cm2 for oxygen and hydrogen evolution reactions, respectively. Furthermore, cobalt sulfide was synthesized using the pervious composite (not carbonized) to compare the water splitting activities for both cobalt oxide and cobalt sulfide. Clear improvement was obtained for cobalt sulfide based on oxygen evolution reaction and hydrogen evolution reaction. Our results suggest that composites of cobalt oxide and polypyrrole can be used as bi-functional materials for energy applications such as for supercapacitors and electrocatalysts for water splitting