Hydrogen sensors made of undoped and Pt-doped SnO2 nanowires

Tin oxide (SnO2) nanowires with a tetragonal structure were formed on oxidized Si substrates by thermal evaporation of tin grains at 900 degrees C. The morphology, crystal structure, and H-2 gas sensing properties of undoped and Pt-doped SnO2 nanowires were investigated. SnO2 nanowires were approximately 30-200 nm in diameter and several tens of micrometers in length. Gas sensors made of undoped, 0.8 wt% Pt-doped, and 2 wt% Pt-doped SnO2 nanowires showed a reversible response to H-2 at an operating temperature of RT-300 degrees C. The sensitivity increased with increasing H-2 concentration. The highest sensitivity of 118 was obtained for 2 wt% Pt-doped SnO2 nanowire sensor to 1000 ppm H-2 at an operating temperature of 100 degrees C. The gas sensing properties of Pt-doped and Pd-doped SnO2 nanowires were also investigated to compare the effect of impurity doping. The results demonstrated that impurity doping improved the sensitivity and lowered the operating temperature at which the sensitivity was maximized (C) 2009 Elsevier B.V. All rights reserved.