Flame-spray-made undoped zinc oxide films for gas sensing applications

Abstract

Using zinc naphthenate dissolved in xylene as a precursor undoped ZnO nanopowders were synthesized by the flame spray pyrolysis technique. The average diameter and length of ZnO spherical and hexagonal particles were in the range of 5 to 20 nm, while ZnO nanorods were found to be 5-20 nm wide and 20-40 nm long, under 5/5 (precursor/oxygen) flame conditions. The gas sensitivity of the undoped ZnO nanopowders towards 50 ppm of NO2, C2H5OH and SO2were found to be 33, 7 and 3, respectively. The sensors showed a great selectivity towards NO2at high working temperature (at 300 °C), while small resistance variations were observed for C2H5OH and SO2, respectively. © 2010 by the authors.