Enhancing Electrochemical CO2 Reduction on Perovskite Oxide for Solid Oxide Electrolysis Cells through In Situ A‐Site Deficiencies and Surface Carbonate Deposition Induced by Lithium Cation Doping and Exsolution

Abstract Solid oxide electrolysis cells (SOECs) hold enormous potential for efficient conversion of CO 2 to CO at low cost and high reaction kinetics. The identification of active cathodes is highly desirable to promote the SOEC's performance. This study explores a lithium‐doped perovskite La 0.6‐ x Li x Sr 0.4 Co 0.7 Mn 0.3 O 3‐ δ ( x = 0, 0.025 0.05, and 0.10) material with in situ generated A‐site deficiency and surface carbonate as SOEC cathodes for CO 2 reduction. The experimental results indicate that the SOEC with the La 0.55 Li 0.05 Sr 0.4 Co 0.7 Mn 0.3 O 3‐ δ cathode exhibits a current density of 0.991 A cm −2 at 1.5 V/800 °C, which is an improvement of ≈30% over the pristine sample. Furthermore, SOECs based on the proposed cathode demonstrate excellent stability over 300 h for pure CO 2 electrolysis. The addition of lithium with high basicity, low valance, and small radius, coupled with A‐site deficiency, promotes the formation of oxygen vacancy and modifies the electronic structure of active sites, thus enhancing CO 2 adsorption, dissociation process, and CO desorption steps as corroborated by the experimental analysis and the density functional theory calculation. It is further confirmed that Li‐ion migration to the cathode surface forms carbonate and consequently provides the perovskite cathode with an impressive anti‐carbon deposition capability, as well as electrolysis activity.