Catalysis of the electrochemical processes on solid oxide fuel cell cathodes

摘要

Three methods of lowering the activation energy of the oxygen reduction reaction at solid oxide fuel cell (SOFC) cathodes are reported: (ⅰ) addition of highly dispersed noble metals ( ≤ 0.1 mg/cm~2) at the La_(0.84)Sr_(0.16)MnO_3 cathode/yttria stabilized zirconia (YSZ) electrolyte interface; (ⅱ) partial substitution of manganese by cobalt in La_(0.79)Sr_(0.16)MnO_3 cathodes, and (ⅲ) combination of (ⅰ) and (ⅱ). In the presence of palladium, the apparent activation energy, E_a, of the oxygen reduction reaction is decreased from 2.2 eV (La_(0.84)Sr_(0.16)MnO_3 without catalyst) to 1.4 eV. A similar effect is observed, when manganese is substituted by 20 mol% Co (La_(0.79)Sr_(0.16)Mn_(0.80)Co_(0.20)O_3), where E_a ≈ 0.9 eV is obtained. In the presence of palladium, with the substitution of manganese by cobalt (method (ⅲ)), no further improvement is achieved.