SnO2 nanowire gas sensors for detection of ppb level NOx gas

Abstract

Until now, SnO2 nanowires have been directly grown on alumina substrates with Au or Au-coated Pt electrodes by a thermal evaporation method using Sn or SnO2 powders under vacuum. However, in this study, SnO2 nanowires were successfully synthesized on the Pt phase of an alumina substrate by a thermal evaporation method using dibutyltin oxide [DBTO, (C4H9)2SnO] even at atmospheric pressure, resulting in nanowire networks between the Pt phases. Ar with 1% O2 was used as carrier gas with a flow rate of 100 mL/min at 900 °C (heating rate of 25 °C/min). The SnO2 nanowires consisted of straight and branched nanowires, and exhibited a SnO2 phase with a tetragonal structure. Both the DBTO and evaporation temperature play an important role on the synthesis of SnO2 nanowires at atmospheric pressure. The SnO2 nanowire sensor fabricated by an evaporation method showed a sensor response of ~ 500 for 0.05 ppm of NO2, being ~ 10 times greater than that of a SnO2 nanoparticle sensor. Furthermore, the SnO2 nanowire sensor showed excellent repeatability and selectivity for NO2 in the presence of SO2, Cl2, and H2S.