Barium Carbonate Nanoparticles as Synergistic Catalysts for the Oxygen Reduction Reaction on La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3− δ Solid‐Oxide Fuel Cell Cathodes

Barium carbonate (BaCO 3 ) nanoparticles have been demonstrated to have excellent synergistic catalytic activity for the oxygen reduction reaction on La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3− δ (LSCF) and LSCF‐SDC (SDC=Sm 0.2 Ce 0.8 O 1.9 ), which are typical mixed conducting electrode materials for solid‐oxide fuel cells (SOFCs). The BaCO 3 nanoparticles were deposited into the porous electrodes through an infiltration/impregnation method with barium acetate as the precursor. Electrochemical impedance analysis indicated that BaCO 3 dramatically reduced the resistance associated with the low‐frequency response, which suggests that BaCO 3 greatly enhances the kinetics of the surface reaction process. Electrical conductivity relaxation experiments revealed that BaCO 3 particles enlarged the oxygen chemical surface exchange coefficient by a factor of up to eight. As a result, the interfacial polarization resistance of both the LSCF and LSCF‐SDC electrodes was greatly reduced, from 0.28 and 0.13 to 0.12 and 0.047 Ω cm 2 , respectively, at 700 °C. In addition, the single‐cell performance was also improved and demonstrated peak power density from 0.66 and 0.71 to 0.73 and 0.81 W cm 2 for the LSCF and LSCF‐SDC cathodes, respectively, at 700 °C. The LSCF electrode infiltrated with BaCO 3 nanoparticles also exhibited higher stability than the bare LSCF electrode in tests conducted under typical SOFC conditions for over 340 h of operation.