Activation/deactivation behavior of nano-NiOx based anodes towards the OER: Influence of temperature

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 (Tp) on the electrocatalytic activity of nickel oxide nanostructures modified glassy carbon (nano-NiOx/GC) electrode towards the OER. Increasing Tp, beyond room temperature (r.t.), results in enhancing the kinetics of the OER demonstrated in the values of the exchange current density (io) and the onset potentials of the OER. The effect of Tp is reflected on the morphology and size of NiOx, that is increasing Tp results in decreasing their particle size. Elevated Tp 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 (Tm).