In Situ Electrochemical Exsolution of FeNi Alloy Nanoparticles on La 0.8 Sr 0.2 Fe 0.95 Ni 0.05 O 3−δ Cathode for CO 2 Electrolysis in Solid Oxide Electrolysis Cells

Solid oxide electrolysis cells (SOECs) constitute an attractive avenue for the conversion of CO 2 into CO, yet an understanding of the evolution of catalytically active sites and the structure–activity relationship in perovskite cathodes is still insufficient. In this work, the electrochemical reconstruction feature of Ni-doped La 0.8 Sr 0.2 Fe 0.95 Ni 0.05 O 3−δ (LSFN) during CO 2 electrolysis with FeNi alloy nanoparticles exsolution on the LSFN surface is investigated, and the structural origin of the high efficiency toward CO 2 electrolysis is unveiled. The resulting FeNi@LSFN cathode achieved a current density of 3.53 A cm –2, which is among the highest values reported in the literature, outperforming its La 0.8 Sr 0.2 FeO 3−δ counterpart without structural reconstruction. Combined experimental characterization and density functional theory calculations demonstrate that moderate Ni doping effectively increases the oxygen vacancy concentration, drives surface reconstruction to construct the active FeNi@LSFN interfaces, and thus facilitates CO 2 activation and conversion. This study demonstrates the promise of electrochemical exsolution during CO 2 electrolysis as a robust strategy for developing efficient and durable perovskite-based cathodes for SOECs.