Spatially Resolved Mapping of Oxygen Reduction/Evolution Reaction on Solid-Oxide Fuel Cell Cathodes with Sub-10 nm Resolution

Spatial localization of the oxygen reduction/evolution reactions on lanthanum strontium cobaltite (LSC0) surfaces with perovskite and layered perovskite structures is studied at the sub-10 nm level. Comparison between electrochemical strain microscopy (ESM) and structural imaging by scanning transmission electron microscopy (STEM) suggests that small-angle grain boundaries act as regions with enhanced electrochemical activity. The ESM activity is compared across a family of LSCO samples, demonstrating excellent agreement with macroscopic behaviors. This study potentially paves the way for deciphering the mechanisms of electrochemical activity of solids on the level of single extended structural defects such as grain boundaries and dislocations.