Three-phase-boundary dynamics at the Ni/ScYSZ interface

Chronoamperometry using a three-electrode cell configuration was undertaken with a nickel point-electrode acting as the working electrode on a polished ScYSZ electrolyte in a hydrogen atmosphere at 750–850 °C. High anodic overpotentials resulted in the occurrence of distinct sawtooth oscillation patterns in the measured current signal. The current oscillations indicated that a dynamic electrode process was taking place. Decreasing the water content in the measurement atmosphere as well as lowering the applied anodic overpotential had the effect of lowering the frequency and the amplitude of the current oscillations. A mechanism accounting for the observed phenomena and possible implications for solid oxide fuel cell operation are presented.