Collective Synergistic Catalysis of Electrochemical CO 2 Reduction on Nonstoichiometric Double Perovskites

Perovskite oxides show great promise as an alternative catalyst to the conventional nickel cermets for CO 2 reduction reactions (CO 2 RR) in solid oxide electrolysis cells (SOECs) owing to their advantages of redox stability and coking resistance. Nevertheless, practical applications of these oxides are prevented largely by their poor CO 2 RR activities. Herein, a novel donor and acceptor co‐doped nonstoichiometric double perovskite, La 0.3 Sr 1.55 Fe 1.5 Ni 0.1 Mo 0.4 O 6− δ (LSFNM), is developed with in situ exsolved FeNi 3 nanoparticles to efficiently catalyze CO 2 RR in SOECs. Pure CO 2 electrolysis over the impregnated FeNi 3 @LSFNM catalysts is evaluated on two types of SOECs—one with thin (ZrO 2 ) 0.89 (Sc 2 O 3 ) 0.1 (CeO 2 ) 0.01 (SSZ) electrolytes supported on 430L alloys and the other with thin La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3− δ (LSGM) electrolytes supported on impregnated SmBa 0.5 Sr 0.5 Co 2 O 5+ δ (SBSCO)@LSGM anodes, producing unprecedently high current densities of 2.84 A cm −2 for the former and 3.07 A cm −2 for the latter at 1.5 V and 800 °C. Experimental analysis and density‐functional theory (DFT) calculations reveal collective synergistic catalysis of oxygen vacancies (), the doping Ni 2+ ions and FeNi 3 nanoparticles via the cooperative ‐O(CO 2 ), and Ni(II)–C(sp) and Ni(0)–O(CO 2 ) interactions in LSFNM, not only facilitating CO 2 chemisorption on oxygen vacancies but also destabilizing and dissociating surface carbonates in the vicinity of FeNi 3 spontaneously into CO.