Anodic polarization behaviour of hydride-deuteride electrodes

TLDR: The results of electrochemical measurements performed on hydrogen absorbing metal electrodes such as LaNi 5− x Al x (x = 0−1.0), MmNi 4 Al (Mm  misch metal), LaNi 4 Cu and TiNi 0.6 are reported in this paper.

Abstract: The results of electrochemical measurements performed on hydrogenabsorbing metal electrodes such as LaNi 5− x Al x ( x = 0−1.0), MmNi 4 Al (Mm  misch metal), LaNi 4 Cu and TiNi 0.6 are reported. The equilibrium hydrogen pressure, partial molar enthalpy ΔH and partial molar entropy ΔS of hydride (or deuteride) formation were calculated on the basis of their electrode potentials. The values determined electrochemically agreed very closely with those obtained from the solid-gas equilibrium. The current is strongly governed by the diffusion process at a large anodic polarization of the hydride-deuteride electrodes. The experimental current-overpotential curves are discussed on the basis of electrode and diffusion theory. In the case of hydride electrodes with a small value of − ΔH the diffusion species are mainly the OH − (or OD − ) ions in the electrolyte solution. As the value of − ΔH increases, the activation energy of diffusion becomes larger and the diffusion species become the hydrogen (or deuterium) atoms in the metal.