Unlocking the Catalytic Activity of Iron via Vanadium‐Mediated Electronic Structure Tuning in Perovskite Fuel Electrodes

The deployment of solid oxide electrolysis cells (SOECs) for grid load regulation and CO 2 utilization faces a persistent challenge: how to achieve high catalytic activity and long‐term structural stability simultaneously in fuel electrodes under harsh co‐electrolysis conditions. In this study, we address this challenge by introducing multivalent vanadium (V) into the B site of the iron‐based perovskite (La 0.5 Sr 0.5 ) 0.95 FeO 3−δ (LSF). Through combined experiments and density functional theory (DFT) calculations, we uncover a dual regulatory effect. V doping modulates the electronic structure of Fe active sites, lowering the oxygen vacancy formation energy; meanwhile, it strengthens lattice stability through robust V─O bonding. This synergy between defect chemistry and thermomechanical integrity allows the optimized fuel electrode, (La 0.5 Sr 0.5 ) 0.95 Fe 0.95 V 0.05 O 3−δ (LSFV 0.05 ), to deliver high electrochemical performance with tunable syngas ratios, where the CO to H 2 ratio can be adjusted from 1.1 to 5.0, and sustain stable operation for over 300 h without carbon deposition or delamination. Our results establish a multivalent cation‐doping strategy that reconciles surface catalysis with bulk stability, offering a pathway toward efficient and durable SOEC electrodes capable of operating under fluctuating grid conditions.