In-situ photoelectron microspectroscopy and imaging of electrochemical processes at the electrodes of a self-driven cell.

The challenges in development of solid oxide fuel cells (SOFCs) are reducing their dimensions and increasing their efficiency and durability, which requires physicochemical characterization at micro-scales of the device components during operation conditions. Recently, the unique potential of scanning photoelectron microscopy (SPEM) has been demonstrated by in-situ studies of externally-driven SOFCs, which mimic real devices. Here we overcome the gap between model and real systems using a single-chamber Ni|YSZ|Mn SOFC, supporting a range of self-driven electrochemical reactions in variable gas environments and temperatures. The reported SPEM results, obtained during spontaneous electrochemical processes occurring in reactive gas ambient, demonstrate the chemical evolution of electrodic material, in particular the lateral distribution of the oxidation state and the induced local potential, clearly marking out the electrochemically most active micro-regions of the Ni anode.