Copper oxide as a synergistic catalyst for the oxygen reduction reaction on La0.6Sr0.4Co0.2Fe0.8O3−δ perovskite structured electrocatalyst

• CuO is used as synergistic catalyst for oxygen reduction reaction on LSCF.
• Enhanced rate is attributed to CuO surface and LSCF-CuO-gas boundaries.
• The contribution of CuO to incorporated oxygen could reach 78%.
• The reduced resistance of LSCF is related to oxygen surface process.
• LSCF and CuO could remain chemical compatible in testing condition.

This work presents the effect of dispersed copper oxide (CuO) nanoparticles on the oxygen reduction reaction (ORR) on a typical solid oxide fuel cell (SOFC) electrocatalyst, La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF). The ORR kinetics were enhanced by a factor up to 4 at 750 °C as demonstrated by electrical conductivity relaxation measurements used to determine the chemical surface exchange coefficient, kchem. The value of kchem increased from 2.6 × 10−5 cm s−1 to 9.3 × 10−5 cm s−1 at 750 °C when the LSCF surface was coated with submicron CuO particles. The enhanced kchem was attributed to additional reactions that occur on the CuO surface and at the LSCF-CuO-gas three-phase boundaries (3PBs) as suggested by the kchem dependence on CuO coverage and 3PB length. This enhancement was further demonstrated by the introduction of CuO nanoparticles into LSCF electrodes. CuO infiltrated electrodes reduced the interfacial polarization resistance from 2.27 Ω cm2 to 1.5 Ω cm2 at 600 °C and increased the peak power density from 0.54 W cm−2 to 0.72 W cm−2 at 650 °C. Electrochemical impedance spectroscopy indicated that the reduced resistance was due to the shrinkage of the low frequency arc, which is associated with the electrochemical surface exchange reaction.