Synergistic Regulation of Lattice Oxygen and Construction of Self-Assembled Heterointerfaces via Fluorine Incorporation for High-Performance CO ₂ Electrolysis in Solid Oxide Electrolysis Cells

Perovskite oxides are promising cathodes for solid oxide electrolysis cells (SOECs), but their strong metal–oxygen bonds restrict lattice oxygen reactivity and induce sluggish CO 2 reduction kinetics. Herein, we propose a synergistic strategy combining an anion activation strategy and self-assembled heterointerface engineering to optimize perovskite La 0.5 Sr 0.5 Fe 0.9 Mn 0.1 O 3-δ (LSFM) cathodes. Fluorine substitution effectively weakens metal–oxygen bonds, promotes oxygen vacancy, accelerates oxygen ion transport, and mitigates Sr segregation. The optimized electrolysis cell delivers a current density of 1.16 A cm –2 at 1.5 V and 800 °C, 65.7% higher than pristine LSFM. Furthermore, a one-pot self-assembled LSFMF10-GDC nanocomposite with abundant heterointerfaces extends the three-phase boundary and boosts charge transfer. It delivers a superior current density of 1.47 A cm –2, high CO selectivity, and excellent long-term stability. This work validates anion doping coupled with interface engineering as a universal approach for designing high-performance SOEC electrodes toward efficient CO 2 electrolysis and sustainable energy conversion.