The Effect of Iodide Ions on the Kinetics of Hydrogen Absorption by Iron

Abstract

The effect of iodide ions on the kinetics of both the hydrogen evolution reaction. HER, and the hydrogen absorption reaction, HAR, on iron (steel) membranes was investigated using an electrochemical hydrogen permeation cell. Iodide ions inhibit the HER by decreasing the rate constant of proton discharge. Iodide enhances the HAR, and in turn increases the concentration of hydrogen inside the metal, although it decreases the hydrogen surface coverage. The increased HAR rate is due to an increase in the composite rate constant of the hydrogen absorption step at the metal surface. © 2000 The Electrochemical Society. All rights reserved.