Oxygen vacancy induced A-site ordering of a superior perovskite ferrite anode for solid oxide fuel cells

Introducing pentavalent niobium stabilizes perovskite lattice of ferrites but reduces oxygen vacancy content. While oxygen vacancies are beneficial for gas adsorption, ion diffusion, and catalytic activity in perovskites, this trade-off is a challenge. Herein, by adjusting A-site rare earth/alkaline earth ratio, we synthesize ABO₃-structured perovskite oxides Pr_0.75Sr_0.25Fe_0.875Nb_0.125O_3-δ (PSFN6271) and Pr_0.5Sr_0.5Fe_0.875Nb_0.125O_3-δ (PSFN4471) and evaluate their electrochemical performance as anodes for solid oxide fuel cells. PSFN4471 undergoes phase transition in reducing environment, from orthorhombic simple perovskite to tetragonal A-site ordered layered perovskite PrSrFe_1.75Nb_0.25O_6-δ (L-PSFN4471), with the exsolution of Fe⁰ nanoparticles. High performance, superior coking and sulfur tolerance are demonstrated for L-PSFN4471 anode. We reveal that oxygen vacancy formation is the driven force for the A-site ordering of PSFN4471 and study the differences between PSFN6271 and PSFN4471 in physiochemical properties and electrochemical performance. We demonstrate that the L-PSFN4471 is a high-performance and promising SOFC alternative anode with considerable coking and sulfur poisoning resistance.