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 °C. The morphology, crystal structure, and H2 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 H2 at an operating temperature of RT–300 °C. The sensitivity increased with increasing H2 concentration. The highest sensitivity of 118 was obtained for 2 wt% Pt-doped SnO2 nanowire sensor to 1000 ppm H2 at an operating temperature of 100 °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.