Surface modification and electrochemical properties of cobalt-based layered perovskite cathodes for intermediate-temperature solid oxide fuel cells

PrBaCo2−xCuxO5+δ (0 ≤ x ≤ 0.2, PBCCO) layered perovskite materials were studied as cathode materials for low-temperature solid oxide fuel cells. The electrical conductivity of PBCCO decreased with an increase in Cu content, and PrBaCo1.8Cu0.2O5+δ (PBCCO20) showed the lowest electrical conductivity of 570 S cm−1 at 750 °C. In order to enhance the kinetics of the oxygen reduction reaction on the surface of PBCCO, Au-decorated PBCCO (Au@PBCCO) having gold nanoparticles on their surface was prepared by sputtering. The TEM-EDS analysis confirmed that gold nanoparticles were uniformly formed on the surface of PBCCO. Cu ions on the PBCCO surface bond with the Au nanoparticles, serving as anchors to maintain the nanoscale particle size even after heat treatment at high temperature. The Au@PBCCO showed a 60% lower polarization resistance value at 700 °C than that of the PBCCO20 due to enhanced ORR activity. We hypothesize that this enhancement is due to the fact that the electron transfer to the surface of PBCCO by the gold nanoparticles is promoted and the reduction of oxygen adsorbed on the surface increased.