SURFACE AND BULK EFFECTS IN THE EXTRACTION OF HYDROGEN FROM HIGHLY LOADED PD SHEET ELECTRODES

It has been shown that hydrogen extraction from highly loaded Pd sheet electrodes takes place under the mixed control of hydrogen diffusion within the solid and kinetic steps at the boundaries. Analysis of the transients of the potentiostatic extraction currents revealed the relevant kinetic and diffusion parameters. The kinetic parameter, which is probably related to the transition H(abs) --> H(ads), thus depends on both the history of the Pd sample electrode and the electrolytic environment, whereas the diffusion parameter may depend on the degree of hydrogen loading in the metal.