Boundary Conditions in Electrochemical Measurements of Diffusion Coefficients of Hydrogen in α-Palladium

Abstract

The boundary conditions in electrochemical hydrogen permeation through α-palladium have been discussed, and then the diffusion coefficients of hydrogen between 278 K and 333 K have been determined. In the permeation experiment, the changes in electrode potential and current density at the cathodic surface have been found to correspond to those in dissolved hydrogen concentration and hydrogen entry flux at the cathodic surface, respectively. The temperature dependence of the diffusion coefficients of hydrogen free from trapping effect and surface effect in annealed α-palladium specimens is given by D_H (m²/s)=2.40×10⁻⁷exp(−21.6(kJ/mol)⁄RT).