Atomic-Scale Insight into Exsolution of CoFe Alloy Nanoparticles in La0.4Sr0.6Co0.2Fe0.7Mo0.1O3-δ with Efficient CO2 Electrolysis.

In situ exsolution of metal nanoparticles in perovskite under reducing atmosphere has been employed to generate highly active metal-oxide interface for CO 2 electrolysis in solid oxide electrolysis cell. Herein, we provide atomic-scale insight into the exsolution of CoFe alloy nanoparticles in La 0.4 Sr 0.6 Co 0.2 Fe 0.7 Mo 0.1 O 3-δ (LSCFM) by in situ scanning transmission electron microscopy (STEM) with energy dispersive X-ray spectroscopy and density functional theory calculations. Atomic-scale STEM images and elemental maps confirm that the doped Mo atoms occupy B sites of LSCFM, which increases the segregation energy of Co and Fe ions at B sites, and improves the structural stability of LSCFM under reducing atmosphere. In situ STEM measurements visualized sequential exsolution of Co and Fe ions and formation of CoFe alloy nanoparticles, as well as reversible exsolution and dissolution of CoFe alloy nanoparticles in LSCFM. The in situ generated metal-oxide interface improves CO 2 adsorption and activation, thus shows a higher CO 2 electrolysis performance than the LSCFM counterparts.