Electrochemical Promotion of Propane and Methane Oxidation on Sputtered Pd Catalyst-Electrodes Deposited on YSZ

Abstract

The microstructure and electrochemical promotion of thin Pd catalyst-electrodes deposited on yttria-stabilized zirconia and prepared by sputter-deposition has been studied for the complete oxidation of propane and methane using steady state catalytic measurements in conjunction to electrochemical studies under lean conditions and at temperatures from 320 to 450 °C. It was found that propane oxidation is favoured on the metallic Pd film, while methane oxidation is enhanced after partial oxidation of the sputtered film in the course of the experiments. The observed rate changes under anodic polarization were strongly non-Faradaic and exceeded the electrocatalytic rate, I/2F, of O2− supply to the catalyst by up to a factor of 150 for methane and 250 for propane combustion. The catalytic rate increases only moderately by up to a factor of 2 and 3, respectively. For both reactions the catalyst-electrodes exhibit electrophobic behaviour, i.e. the rate increases with anodic polarization and decreases slightly with cathodic polarization.