Achieving Fast Reconstruction of Metal/Ruddlesden‐Popper Layered Perovskite Heterointerfaces via Structural Flexibility‐Driven Phase Transition Engineering for Efficient and Durable CO ₂ Electrolysis

In situ constructing active metal/oxide interfaces has extensive applications for CO₂ electrolysis in solid oxide electrolysis cells (SOECs) but faces critical challenges due to sluggish diffusion process of B-site cations inside the perovskite bulk. Herein, the diffusion kinetics of Fe and Ni cations in Sr_0.9Ti_0.45Fe_0.5Ni_0.09O_3-δ (S_0.9TFN_0.09) are greatly facilitated via structural flexibility. The synergistic modification of Sr-site defects and excess Ni incorporation enables flexible coordination and enhanced intrinsic oxygen properties, driving a bulk-surface reconstruction under reducing condition. As a consequence, the heterostructured FeNi alloy (FNA) and metallic Fe nanoparticles are readily in situ exsolved onto Ruddlesden-Popper layered perovskite (RP-STF) surface. The phase transition process significantly increases the number of exsolved particles. Compared with pristine matrix, the reconstructed FNA/Fe@RP-STF interfaces deliver markedly enhanced electrocatalytic activity for CO₂ adsorption and dissociation, thus reach a 51% improvement in CO₂ electrolysis performance at 1.5 V and 800 °C. Moreover, the operating stability and anticoke properties are enhanced due to strongly interactive heterointerfaces. This work provides a sufficiently simple strategy to rapidly achieve microstructural evolution for CO₂ electrolysis and other energy conversion.