Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Physical Chemistry

Electrocatalysis at nanostructured materials is a topic of a great interest, due to the high surface area to volume ratio that increases the overall performance, while minimizing costs of often expensive metal and alloy constituents. Sensitivity of electrocatalytic reactions to the catalyst particle size, loading and crystallographic orientation has been reported for the oxygen evolution reaction (OER) at various temperatures (a reaction with direct relevance to energy conversion applications). Nanostructured nickel oxide modified glassy carbon electrodes (nano-NiOx/GC) are used as the anodes. The influence of temperature (T) on the activity of the electrode was probed. Increasing T results in a significant enhancement of the catalytic activity of nano-NiOx/GC as probed by a favorable negative shift of the onset potential (Eonset) of the OER, and an increase of the OER current at a particular potential. Moreover, nano-NiOx/GC passivated at elevated temperatures (e.g., 333 K) shows better catalytic activity and stability towards the OER more than those prepared at lower temperature (298 K). However, a rapid degradation of activity upon prolonged electrolysis at elevated temperatures is observed which could be restored (partially or totally) upon cycling the potential of nano-NiOx/GC electrode several times between (0.85 and 1.65 V vs RHE)

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