Electrode polarization at the Pd/proton conductor interface

The electrode kinetics at the Pd/proton conductor interface were studied using two solid state proton conductors, SrCe0.95Yb0.05O3−α and SrZr0.95Y0.05O3−α. A three-electrode single chamber cell was used to obtain current-overpotential curves at temperatures between 400 and 700 °C and at hydrogen partial pressures between 1 kPa and 100 kPa. Limiting currents were observed in most cases. The high field approximation of the Butler-Volmer equation was used to fit the experimental results and calculate the exchange and limiting current densities and the charge transfer coefficients. The effect of temperature and gas composition on the exchange and limiting current was studied.