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 CO2 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 La0.8Sr0.2Fe0.95Ni0.05O3−δ (LSFN) during CO2 electrolysis with FeNi alloy nanoparticles exsolution on the LSFN surface is investigated, and the structural origin of the high efficiency toward CO2 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 La0.8Sr0.2FeO3−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 CO2 activation and conversion. This study demonstrates the promise of electrochemical exsolution during CO2 electrolysis as a robust strategy for developing efficient and durable perovskite-based cathodes for SOECs.