LAUSR

Abstract Ni-based catalysts have shown promise activity towards the oxygen evolution reaction (OER). The stability and the activity of the Ni-based catalysts are crucial parameters that gained a lot of interest recently. This paper addresses the effect of the preparation temperature ( T p ) on the electrocatalytic activity of nickel oxide nanostructures modified glassy carbon (nano-NiOx/GC) electrode towards the OER. Increasing T p , beyond room temperature ( r.t. ), results in enhancing the kinetics of the OER demonstrated in the values of the exchange current density ( i o ) and the onset potentials of the OER. The effect of T p is reflected on the morphology and size of NiOx, that is increasing T p results in decreasing their particle size. Elevated T p enhances the OER as a result of increasing the population of the electroactive NiOx phases as indicated from their respective XRD patterns. Rapid degradation of the catalytic activity of nano-NiOx/GC electrode towards the OER is observed upon prolonged electrolysis at r.t. Cycling the potential several times between 0.85 and 1.65 V vs. RHE restores the activity to various extents depending on the measurement temperature ( T m ).