SnO2 nanowire gas sensors for detection of ppb level NOx gas

Until now, SnO 2 nanowires have been directly grown on alumina substrates with Au or Au-coated Pt electrodes by a thermal evaporation method using Sn or SnO 2 powders under vacuum. However, in this study, SnO 2 nanowires were successfully synthesized on the Pt phase of an alumina substrate by a thermal evaporation method using dibutyltin oxide [DBTO, (C 4 H 9 ) 2 SnO] even at atmospheric pressure, resulting in nanowire networks between the Pt phases. Ar with 1% O 2 was used as carrier gas with a flow rate of 100 mL/min at 900 °C (heating rate of 25 °C/min). The SnO 2 nanowires consisted of straight and branched nanowires, and exhibited a SnO 2 phase with a tetragonal structure. Both the DBTO and evaporation temperature play an important role on the synthesis of SnO 2 nanowires at atmospheric pressure. The SnO 2 nanowire sensor fabricated by an evaporation method showed a sensor response of ~ 500 for 0.05 ppm of NO 2 , being ~ 10 times greater than that of a SnO 2 nanoparticle sensor. Furthermore, the SnO 2 nanowire sensor showed excellent repeatability and selectivity for NO 2 in the presence of SO 2 , Cl 2 , and H 2 S.