Rate Analysis by Potential-step Chronoamperometry in Pt/YSZ Air Cathodes

Abstract

This study aims to separate the polarization resistance of Pt/YSZ air electrodes into two resistance components, i. e., dissociative adsorption resistance and diffusion resistance. Current decay curves were measured by potential-step chronoamperometry and a current decay equation was obtained by solving Fick's diffusion equation under appropriate boundary conditions. The experimental decay curves were fitted to the equation by optimizing parameter values involved in the equation. Diffusion coefficients and rate constants for adsorption were calculated from the parameter values thus obtained. It was found that the rate controlling step depends on temperature, oxygen pressure and sintering temperature of electrodes.