Fluorite-Perovskite Heterointerface Engineering Boosts CO₂ Electrolysis Performance in Solid Oxide Electrolysis Cells

Solid oxide electrolysis cells (SOECs) provide a promising route for renewable-electricity storage and CO₂ conversion into value-added chemicals and fuels, yet their high-temperature operating environment requires the development of efficient and stable fuel electrode materials. Sr_0.9Ti_0.45Fe_0.5W_0.05O_3-δ (STFW) perovskite material fabricated in our previous work shows a promising SOEC fuel electrode and is expected to be further optimized. Herein, we develop a heterointerface engineering strategy by infiltrating fluorite-type Pr_0.1Ce_0.9O_2-δ (PCO) into the porous STFW fuel electrode, constructing a highly active PCO-STFW composite fuel electrode. The optimized 30PCO-STFW (30 μL PCO) electrode achieves a polarization resistance of 0.14 Ω cm² at 800 °C. A single cell employing 30PCO-STFW as the fuel electrode delivers an electrolysis current density of 1.33 A cm^-2 at 800 °C and 1.5 V, which is 23% higher than that of the STFW cell. Moreover, the 30PCO-STFW cell maintains relatively stable operation at 800 °C and 1.2 V for 70 h. This study demonstrates that PCO-enabled fluorite-perovskite interfacial engineering effectively regulates the surface reaction environment of STFW fuel electrodes, providing an effective strategy for improving CO₂ electrolysis performance in SOECs.