In situ Construction of Metal/Perovskite Interfaces with Exsolved FeNi Alloy Nanoparticles for High-Temperature CO₂ Electrolysis

Solid oxide electrolysis cells (SOECs) show potential applications in CO₂ utilization and renewable energy resources storage due to their fast kinetics and high energy efficiency. However, the absence of active and stable electrode materials has limited the practical applications of SOECs for CO₂ electrolysis. Herein, FeNi alloy nanoparticles anchored on a La_0.6Sr_0.4Fe_0.85Ni_0.05Nb_0.1O_3‑δ (LSFNN) perovskite surface were developed by controlling appropriate in situ exsolution conditions for CO₂ electrolysis. The FeNi@LSFNN-based SOEC showed current densities of 0.57 A cm^–2 at 700 °C and 1.16 A cm^–2 at 800 °C at 1.6 V, which are 1.39 and 1.18 times those of the pristine LSFNN-based cell, respectively. The distribution of relaxation time analysis of electrochemical impedance spectra and CO₂ temperature-programmed desorption results indicate that the in situ constructed FeNi@LSFNN interfaces with abundant oxygen vacancies promote the adsorption, activation, and dissociation of CO₂ molecules, thus improving the CO₂ electrolysis performance of SOECs.