Investigation of new materials for redox flow batteries

In this dissertation, MnO2, NiO and Cu2O metal oxide electrocatalysts were electrochemically synthesized on the surface of pencil graphite electrode (PGE), which is a carbon-based electrode, with the mean of CV by electrodeposition. In this scope, the synthesis potenatial range (V), acid concentration (M) as the supporting electrolyte, metal oxide precursor concentration (M) and number of cycles were investigated to form metal oxide on the PGE surface. Modified electrodes were electrochemically characterized via CV and EIS and interpreted the surface and the structure by SEM/EDX, XRD and XPS. The activity of metal oxide modified electrodes was evaluated by the differences between anodic and cathodic peak potentials (∆V, V) and charge transfer resistances (Rct, Ω). The optimum conditions to modify raw PGE as MnO2 metal oxide were observed ‒0.5/1.5 V as potential range; 3 M H2SO4 as supporting electrolyte medium; 0.5 M KMnO4 precursor concentration and 50 cycles. For NiO modified PGE, the optimum conditions were 0/1.2 V as the potential range for synthesis; 2 M H2SO4 as acid concentration; 0.1 M NiSO4 as metal oxide source concentration and 50 cycles as the cycle number. The optimum conditions among selected values for modification as Cu2O on PGE were found ‒0.5/1.5 V as the potential range; 3 M HNO3 for supporting electrolyte as acid concentration; 0.5 M CuSO4 metal oxide source medium and 100 cycles as cycle number. The presence of metal oxides were supported by SEM/EDX, XRD and XPS.