The Influence of Potential and Temperature on the Kinetics of Oxygen Reduction on Alloy 22 in Neutral Chloride Solutions.

Abstract

The passive film on Alloy 22, and its influence on the kinetics of oxygen reduction, has been studied in neutral 5 mol dm-3 NaCl at temperatures from 30oC to 90oC using Electrochemical Impedance Spectroscopy, X-Ray Photoelectron Spectroscopy and Cyclic Voltammetry. The impedance is very dependent on potential but only slightly dependent on temperature. Passivity is maximized, and oxygen reduction most suppressed, over the potential range -0.2 V to 0.2 V. At higher potentials the passive film resistance decreases markedly, leading to catalysis of oxygen reduction in the range 40oC to 60oC. At higher temperatures catalysis is lost.