One-step fabrication of SnO2 porous nanofiber gas sensors for sub-ppm H2S detection

SnO2 porous nanofibers (NFs) were deposited on-chip by using a facile electrospinning method followed by heat treatment at 600 degrees C and used to detect H2S concentrations at sub-parts per million level. Morphological, compositional, crystal, and atomic structural properties of the as-spun and calcined SnO2 NFs were investigated by field emission electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy, respectively. SnO2 porous NFs with an average diameter of 150 nm and consisting of many nanograins were successfully fabricated by on-chip electrospinning. The NFs were crystallized as the tetragonal structure of SnO2 with an average crystallite size and dislocation density ofapproximately 13.5 nm and 5.615 x 10(15) lines/m(2), respectively. The sensing characteristics of the SnO2 NF sensors were tested with 0.1-1 ppm H2S from 150 degrees C to 450 degrees C. The sensor achieved the optimal performance at 350 degrees C and exhibited gas response of 15.2 with fast response/recovery times of 15 s/230 s. The H2S gas sensing mechanisms of the SnO2 porous NF sensors were due to the modulation of the resistance along the surface depletion layer and the grain boundaries. The fabricated sensor also indicated a good selectivity to H2S, short-term stability, and the low detection limit of 1.6 ppb. The influence of humidity on the sensor's performance in a low temperature range is also discussed. (C) 2019 Elsevier B.V. All rights reserved.