Film thickness effects on hydrogen sorption at palladium electrodes

Abstract

Hydrogen sorption at thin film evaporated Pd electrodes is quite different from that at bulk Pd. Diffusion of dissolved hydrogen in the thin films is slow. The grain size of the evaporated films is small, and the large number of grain boundaries present a high resistance to hydrogen diffusion. Thin films sorb a greater quantity of hydrogen than bulk Pd. Annealing of the evaporated films, due to an increase in grain size, results in hydrogen sorption behavior resembling that of bulk Pd and a decrease in the charge due to sorbed hydrogen. The dependence of sorption charge on Pd morphology could be explained by segregation of sorbed hydrogen at grain boundaries. © 1980 Elsevier Sequoia S.A.