High La/Sr ratio in La0.67Sr0.33Fe0.67Ti0.33O3-δ cathode induced a controlled Fe0 exsolution for CO2 electrolysis

This study aimed at improving electrocatalytic activity of solid oxide electrolysis cell (SOEC) cathode via in-situ exsolved nanoparticles. La 0.67 Sr 0.33 Fe 0.67 Ti 0.33 O 3-δ (LSFT) and La 0.67 Sr 0.33 Fe 0.6 Ni 0.067 Ti 0.33 O 3-δ (LSFNT-67) cathodes with a La/Sr ratio about 2.0 showed the exsolution of Fe 0 and FeNi 3 alloy nanoparticles, respectively, under a reducing atmosphere. The SOEC with LSFT of electrocatalysis is better than LSFNT-67 at 800 °C for direct electrolysis of CO 2 , the current density of LSFT and LSFNT-67 reach − 0.54 A cm −2 and − 0.29 A cm −2 , respectively, and the Faradaic efficiency is close to unity during the 25 h′ durability under a − 1.3 V bias. The better cell performance for the cell with LSFT than LSFNT-67 could be related to the larger distortion and the less amount of insulating LaSrGa 3 O 7 in the former, causing its unexpectedly larger quantity of metal exsolution and electron conduction for more active reaction sites for CO 2 activation. This work demonstrated that apart from thermodynamic consideration, steric effect of the B site cation could be important for the exsolution of metal particles from a perovskite with high La/Sr ratio and the resultant electrocatalysis of CO 2 electrolysis.