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