Highly Active and Thermally Stable Core-Shell Catalysts for Solid Oxide Fuel Cells

The effect of catalyst nanostructure on the performance of solid oxide fuel cell (SOFC) anodes prepared by infiltration of an electronic conductor (45 wt % La 0.8 Sr 0.2 Cr 0.5 Mn 0.5 O 3 , LSCM) and a catalyst (1 wt % Pd and 9 wt % CeO 2 ) into porous yttria-stabilized zirconia (YSZ) scaffolds was examined. When Pd and CeO 2 were added by classical infiltration with nitrate salts, the initial electrode impedance in 97% H 2 -3% H 2 O at 973 K was ∼0.1 Ω cm 2 ; however, the impedance was found to increase significantly with time at 973 K and with heating to 1173 K. SEM images showed that the loss of performance coincided with a large increase in the size of the Pd crystallites. When Pd@CeO 2 dispersible core-shell structures obtained through self-assembly were infiltrated into the anode and used as the catalytic component, the initial performance was excellent and the activity was remarkably stable with time at 973 K and upon heating to 1173 K. The improved stability is shown to be the result of greatly suppressed particle-size growth for Pd@CeO 2 within the electrode structure. This study highlights the potential use of core-shell materials as stable structures in various fields of materials science and heterogeneous catalysis.