Physicochemical origins of electrochemical promotion of LSM/YSZ

A complex route provided powders of La1−xSrxMnO3 (x = 0, 0.15, 0.3 and 0.4) from the thermal decomposition of the chelated nitrate precursors. The catalysts were characterized by XRD, BET, SEM, and temperature-programmed techniques. Electrochemical catalysts based on La0.7Sr0.3MnO3 (LSM) were deposited on yttria-stabilized zirconia (YSZ) pellets. Electrochemical characterizations of these samples evidenced two redox processes assigned to the existence of different environments around Mn4+ in LSM in good agreement with the peaks observed by temperature programmed reduction (TPR). In situ O2 temperature programmed desorption (O2-TPD) and temperature programmed oxidation (TPO) of propane were performed on LSM/YSZ to investigate the influence of the polarization on oxygen and propane chemisorption on LSM/YSZ. O2-TPD experiments have shown that the electrical polarization during adsorption process has no significant impact on gaseous oxygen adsorption on LSM thin film. TPO experiments suggest an increase in the adsorption strength of propane on LSM that could be at the origin of the electrochemical promotion effects observed upon polarization conditions.