Ni and F Co-doped A-site Deficient Perovskite Nanofibers with Enhanced Catalytic Performance for CO/CO2 Atmospheres in Reversible Solid Oxide Fuel Cells

Developing robust fuel electrodes with high catalytic activity and stability under CO/CO 2 atmospheres is critical for reversible solid oxide fuel cells (RSOFCs). Here, we report a novel A-site-deficient perovskite Sr 1.95 Fe 1.5 Mo 0.3 Ni 0.2 F 0.1 O 6-δ (SFMNF) synthesized via electrospinning, combining Ni 2+ (B-site cation) and F - (anion) co-doping to enhance CO 2 electrolysis and syngas oxidation performance. Physicochemical characterization reveals that F-doping lowers the crystallization temperature, increases oxygen vacancy concentration, and strengthens CO 2 chemisorption. Reduction under H 2 induces exsolution of Ni 3 Fe alloy nanoparticles. The SFMNF electrode achieves a current density of 233 mA cm -2 at 1.3 V and 750°C in CO:CO 2 =2:1 atmosphere, with 36.2% higher activity than the pre-reduced state. Electrochemical impedance and distribution of relaxation time analyses identify CO 2 adsorption/dissociation as the rate-limiting step. The cell demonstrates exceptional durability over 50 redox cycles and 85-hour of operation without carbon deposition. This work highlights dual doping as an effective strategy to tailor perovskite properties for efficient CO 2 utilization in RSOFCs.