Electrochemical response of highly porous percolative cgo electrospun membranes

Electrochemical Impedance Spectroscopy (EIS) is here used to characterize highly porous Ce_0.9 Gd_0.1 O_1.95 (CGO, ca. 90% vol. of porosity) free-supporting nano-fibrous thick (100 µm) membranes, fabricated via an electrospinning technique. The investigation of the calcination temperature influence on the microstructure indicates an evolution of the single nanofiber’s microstructure with a gradual grain growth from densely packed polycrystalline to pearl collar-like structures at increasing temperatures. This evolution is accompanied by brittleness for samples treated at temperatures above 800^◦ C. The electrochemical characterization suggests an ionic percolative conductivity that exploits both the bulk-lattice conduction along the individual nanofibers and interfacial conduction across different nanofibers at their intersections. Optimized membranes treated at 600 and 700^◦ C exhibit a similar electrochemical bulk response, but different interfacial electrochemical behavior (low frequency) associated with a grain size effect.