Changes of electrode potential and electrical resistance as a function of the hydrogen content of some Pd+Ni and Pd+Rh alloys

Abstract

Electrode potentials E and relative electrical resistance R/R₀ were measured whilst hydrogen was both absorbed and desorbed by palladium-rich Pd+Ni and Pd+Rh alloys immersed in aqueous solutions at temperatures within the range 0–50°C. Hydrogen contents were determined by outgassing specimens in vacuo, and also from considerations of the changes of E and R/R₀ with time, under conditions where the absorption and/or desorption of hydrogen was governed by the diffusion of either hydrogen or oxygen molecules, through the Brunner-Nernst layer. From the relationships obtained between E, R/R₀ and hydrogen content, further relationships also were derived between hydrogen content and hydride vapour pressure p. The relationships between hydrogen content and the other parameters generally were found to exhibit an absorption/desorption hysteresis.