Voltammetric Studies of the Mechanism of the Oxygen Reduction in Alkaline Media at the Spinels Co3O4 and NiCo2O4

The mechanism of O2 reduction at the spinels, Co3O4 and NiCo2O4, in KOH electrolyte is probed using voltammetry at rotating disc and rotating ring-disc electrodes by examination of the rotation rate dependent limiting currents. The analysis shows that the products and mechanisms at the two spinels a...

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Bibliographic Details
Published in:Journal of the Electrochemical Society 2016-01, Vol.163 (10), p.H884-H890
Main Authors: Sönmez, Turgut, Thompson, Stephen J., Price, Stephen W. T., Pletcher, Derek, Russell, Andrea E.
Format: Article
Language:English
Online Access:Get full text
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Summary:The mechanism of O2 reduction at the spinels, Co3O4 and NiCo2O4, in KOH electrolyte is probed using voltammetry at rotating disc and rotating ring-disc electrodes by examination of the rotation rate dependent limiting currents. The analysis shows that the products and mechanisms at the two spinels are quite different. At the cobalt spinel, a substantial amount of the 2e− reduction product, H2O2, is formed while at NiCo2O4 the 4e− reduction strongly predominates. In terms of both the overpotential for reduction and its limiting current density, the mixed spinel is a substantially better electrocatalyst. It is proposed that the differences arise from an enhanced rate of O-O bond cleavage early in the reduction process at NiCo2O4.
ISSN:1945-7111
DOI:10.1149/2.0111610jes