High performance ethanol sensing films fabricated from ZnO and In2O3 nanofibers with a double-layer structure

► Double-layer structure is firstly employed in nanofiber-based gas sensors. ► Decreased optimum temperature and enhanced sensitivity are obtained. ► Response and recovery times are only 1 and 2 s to 100 ppm ethanol, respectively. ► Effects of the layer structure on sensor performance are discussed.