Growth and ammonia sensing properties of Zn1-xSnxO nanofibers

Randomly oriented Sn-doped ZnO (Zn1-xSnxO) nanofibers have been synthesized by a facile evaporation and re-condensation technique using metallic Sn and Zn as precursors in Ar-2% O-2 atmosphere at 850 degrees C on Si substrates. The dimension of the Zn1-xSnxO nanofibers ranges from 100 nm to 200 nm in diameters and lengths up to few mm. The XRD patterns reveal a set of distinct diffraction peaks indexed as the wurtzite hexagonal ZnO phase. The growth mechanism is dominated by a catalyst-free vapor solid process and the preferred growth direction of Sn-doped ZnO nanofibers is along the [0 0 0 1] direction. The NH3 sensing properties of the as-deposited nanostructures are investigated for different vapor concentrations (10, 25, 50, 100 and 200 ppm) and working temperatures (200, 250, 300, 350 degrees C). Zn1-xSnxO nanofibers are found to possess better sensitivity toward the ammonia vapor as compared to pristine or undoped ZnO nanowires at identical experimental conditions. The gas sensing mechanism of the nanostructures has been discussed in detail. The high sensitivity and dynamic reproducibility of these sensor materials reveal that this composition and morphology can be applied to fabricate sensing devices for detecting ammonia vapor at low to medium concentration range. (C) 2015 Elsevier B.V. All rights reserved.