Electrospun Ni-doped SnO2 nanofiber array for selective sensing of NO2

Ni-doped SnO 2 nanofiber array was prepared from a modified electrospinning technique followed with hot-press and calcination, which impart the nanofiber with high crystallinity as well as good adhesion to the substrate. The nanofiber array consists of well-aligned straight fibers with an average diameter of ∼200   nm and length of several millimeters. Each fiber consists of rutile-structured polycrystals with an average grain size of ∼5   nm. Conductometric gas sensors were developed from the nanofiber array using magnetron sputtering. These sensors show excellent performance for NO 2 detection at 250   °C, including high response (90.3 under 20   ppm), fast response and recovery (40 s/18   s), and above all, excellent selectivity. Beneficial for electron transport, the nanofiber array offers better device performance over random nanofibers on sensing response and time for recovery. In addition, the NO 2 sensing mechanism was probed with detailed DRIFT and XPS analysis.