AbstractMetal nanoparticles anchored on perovskite through in situ exsolution under reducing atmosphere provide catalytically active metal/oxide interfaces for CO₂ electrolysis in solid oxide electrolysis cell. However, there are critical challenges to obtain abundant metal/oxide interfaces due to the sluggish diffusion process of dopant cations inside the bulk perovskite. Herein, we propose a strategy to promote exsolution of RuFe alloy nanoparticles on Sr₂Fe_1.4Ru_0.1Mo_0.5O_6−δ perovskite by enriching the active Ru underneath the perovskite surface via repeated redox manipulations. In situ scanning transmission electron microscopy demonstrates the dynamic structure evolution of Sr₂Fe_1.4Ru_0.1Mo_0.5O_6−δ perovskite under reducing and oxidizing atmosphere, as well as the facilitated CO₂ adsorption at RuFe@Sr₂Fe_1.4Ru_0.1Mo_0.5O_6−δ interfaces. Solid oxide electrolysis cell with RuFe@Sr₂Fe_1.4Ru_0.1Mo_0.5O_6−δ interfaces shows over 74.6% enhancement in current density of CO₂ electrolysis compared to that with Sr₂Fe_1.4Ru_0.1Mo_0.5O_6−δ counterpart as well as impressive stability for 1000 h at 1.2 V and 800 °C.