Co-substituted Sr_2Fe_(1.5)Mo_(0.5)O_(6-δ) as anode materials for solid oxide fuel cells: Achieving high performance via nanoparticle exsolution

摘要

Co-Substituted Sr2Fe1.5Mo0.5O6-delta (Sr2Fe1.3Co0.2Mo0.5O6-delta) double perovskite oxides have been prepared and evaluated as anode materials of solid oxide fuel cells (SOFCs). In reducing atmosphere, active cobalt metal nanoparticles are in situ exsolved from the parent double perovskite oxides, which are characterized by XRD, XPS, SEM and TEM. Sr2Fe1.3Co0.2Mo0.5O6-delta show the highest electrical conductivity of 13.9 S cm(-1) at 600 degrees C and the lowest polarization resistance of 0.15 Omega cm(2) at 850 degrees C in 5% H-2-95% N-2. When hydrogen, syngas and methane are filled as fuel, a maximum power density of 1.09, 0.981 and 0.29 W cm(-2) could be achieved at 850 degrees C, respectively. Further, after continuously operated in hydrogen for 115 hs, in syngas for 190 hs and in methane for 300 hs, there are no negligible degradations. Synergistic effect between perovskite oxide and exsolved Co nanoparticles contributes to the improved SOFCs performances. The protocol developed in this research provides a new strategy to optimize anodic activities of double perovskite oxides, and broadens our horizons in rational design of heterogeneous ceramics for other applications.