Building Efficient and Durable Hetero‐Interfaces on a Perovskite‐Based Electrode for Electrochemical CO₂ Reduction

Solid oxide electrochemical cells (SOECs) have demonstrated the potential to be highly efficient devices for electrochemical CO 2 reduction (CO 2 R) at intermediate temperatures. However, the performance and widespread applications for CO 2 R largely hinge on the sluggish reaction kinetics and poor durability of the state‐of‐the‐art electrodes. Here, the findings in enhancing the reaction activity and durability of a perovskite‐based electrode are reported, Sr 2 Fe 1.5 Mo 0.3 Cu 0.2 O 6‐δ (SF1.5MC), for electrochemical oxidation of H 2 and reduction of CO 2 . Under typical operating conditions, the SF1.5MC electrode is elegantly reconstructed into three phases of oxygen vacancy‐rich double perovskite (DP), Ruddlesden‐popper (RP), and Cu‐Fe metals, as confirmed by X‐ray diffraction and scanning transmission electron microscopy. When applied as a fuel electrode for an electrolyte‐supported SOEC, decent performances are demonstrated at 800 °C, showing a maximum power density of 1.51 W cm −2 in fuel cell mode (on H 2 fuel) and a current density of 1.94 A cm −2 at 1.4 V in electrochemical CO 2 R to CO with high Faradaic efficiencies of ≈100% and good durability.