Aligne d nanofib ers incorporate d composite solid electrolyte for high-sensitivity oxygen sensing at medium temperatures

otentiometric oxygen sensors have been widely used in internal combustion engines,industrial boilers,and metallurgical heat treatment furnaces.However,traditional oxygen sensors based on yttria-stabilized zirconia(YSZ)electrolyte can only be operated at elevated temperatures(>750℃)due to their rela-tively low ionic conductivity.In this study,we present a highly efficient micro-oxygen sensor that can be operated at a temperature as low as 300℃.This micro-oxygen sensor incorporates a composite solid electrolyte,i.e.,well-aligned gadolinium-doped cerium oxide(CGO)nanofibers embedded within a YSZ matrix(YSZ/CGO_(f)).The arrays of CGO nanofibers in the YSZ matrix are parallel to the conduction direc-tion,providing rapid conducting channels for oxygen ions.Benefitting from this design,the composite electrolyte leads to a conductivity of four times higher than that of traditional YSZ solid electrolytes at low temperatures.This enhancement in conductivity is attributed to the presence of a defective interfacial region between CGO_(f)and YSZ,which promotes the mobility of oxygen ions.The strategy of constructing fast ionic conduction in the composite electrolyte by using well-aligned nanofibers may be considered for the design and optimization of other micro/nano-devices including sensors,batteries,and fuel cells.