Anomalous Electrical Conductivity of Nanosheaves of CeO2

CeO2 is a functional oxide known to conduct oxygen ions at elevated temperatures. Enhancement of the ionic conductivity can lead to its application as an electrolyte for solid oxide fuel cells that can operate at low temperatures. We report here a one-dimensional CeO2 nanostructure with a novel sheaflike morphology which exhibits the oxygen-ionic conductivity distinctively higher than that of conventional CeO2 electrolyte. The oxygen nonstoichiometry in the CeO2 nanowires constituting the sheaf was determined by electron energy loss spectroscopy (EELS) and was found to be very small. We thus attribute this anomalously high ionic conductivity to enhanced oxygen-ion mobility at the interfaces between CeO2 nanowires in the sheaf rather than to increased charge-carrier concentration which is often responsible for enhanced ionic conductivity in nanostructured ionic conductors.