Browsing by Author "Thilakarathne, W. A. N. D."

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Fabrication of reduced Graphene oxide - Zinc oxide electrode for supercapacitor applications
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Thilakarathne, W. A. N. D.; Jayawardena, S.
Scientists are concentrating on developing superior hybrid supercapacitors as an alternate form of energy storage in response to the depletion of fossil fuel sources to fulfill the rising demand for energy storage. In this study, supercapacitive properties of reduced graphene oxide (rGO)-Zinc Oxide (ZnO) hybrid composites were analyzed, where ZnO nanoparticles were prepared using the sol-gel method with zinc acetate as the precursor and rGO was obtained via thermal reduction of graphene oxide synthesized using the modified Hummer’s method. Three rGO-ZnO nanocomposites were prepared with varying weight compositions of rGO at 20%, 50%, and 80% content using a cost effective ultrasonic assisted method as an electrode material for supercapacitor application. Thin layers of each hybrid material, ZnO and rGO were coated on FTO glasses using the interfacial method to fabricate the electrodes. The prepared nanocomposites, ZnO, and rGO were characterized using XRD, FESEM, and FTIR. The XRD was used to confirm the formation and the structure of rGO-ZnO nanocomposites as well as the formation of rGO. FESEM images provided compelling evidence illustrating the successful attachment of ZnO nanoparticless onto the surface of rGO sheets. Through FTIR analysis, the presence of specific functional groups in ZnO, rGO and the hybrid composites were determined and thereby confirmed successful hybridization of the materials. Moreover, the open circuit potential and specific capacitance measurements were conducted for each hybrid composite, ZnO and rGO to evaluate the potential superiority of these materials as supercapacitors. Open circuit potential value for 50% rGOZnO hybrid composite has the highest value among the three composites, which is 148 mV. Cyclic voltammetry was done in the potential range of -0.1 V to 1 V under 50 mVs-1 sweep rate using KCl as the electrolyte. The specific capacitance for 20%, 50%, and 80% rGO-ZnO nanocomposites are 122 Fg- 1, 224 Fg-1, and 62.5 Fg-1 respectively. Among the three rGO-ZnO composites, 50% composite has the highest specific capacitance, which is greater than the specific capacitance of 205 Fg-1 for ZnO and 164 Fg-1 for rGO, confirming its superiority as a supercapacitor material. This is due to the positive synergistic effects arising from the integration of pseudocapacitance and double-layer capacitance. These electrochemical methods suggest that hybridizing rGO and ZnO to 50% rGO composition makes an exceptional electrode material for supercapacitor application.