Perovskites based on La(Sr)-Mn-O system as electrocatalyst in PEM fuel cell of high temperature

摘要

In this work, perovskites based on La_(1-x)MnO_(3+δ) and La_(1-y)Sr_yMnO_(3+δ) systems were synthesized by the combustion method, where the rhomboedric phase is reached at 600℃. These synthesized perovskites present sponge type morphology with specific surface areas higher than 10 m~2/g, and nanometric crystal sizes (15-41 nm). The combustion synthesis allows using a lower temperature of calcination maintaining the nanometric features of the powders while well-crystalized phases are achieved. The conductivity was measured on the powders hand compacted, in order to obtain information of its behaviour comparative to the texture of the PEMFC electrode. Finally, cyclic voltammetry was used to study the stability of the perovskites and their catalytic activity towards the ORR, the results indicate that from all the compositions prepared La_(0.7)Sr_(0.3)MnO_3 and La_(0.98)MnO_3 show the most interesting results, with the appearance of a cathodic current that indicates the activity of these catalysts towards the ORR at operation temperature of HTPEMFC.