Double Layer Capacitance of Porous Platinum Electrodes in Zirconia Electrochemical Cells

Abstract

The capacitance of the double layer at the interface between porous platinum electrodes and yttria‐stabilized zirconia has been measured by potential step chronoamperometry. The capacitance is independent of oxygen partial pressure and electrode potential and increases from 0.2 μF/cm2 at 555°C to 1.3 μF/cm2 at 695°C. These values are at least an order of magnitude smaller than capacitances extracted from the low‐frequency portion of ac impedance spectra. This indicates that the capacitive behavior of platinum electrodes in zirconia cells is dominated by time‐dependent faradaic processes.