Nanosized tin oxide as the novel material with simultaneous detection towards CO, H2 and CH4

Gas sensors consisting of nanosized tin oxide prepared from the supercritical fluid drying (SCFD) technique were found operable at lower temperatures. In this study, gas-sensor characteristics of tin oxide consisting of different particle sizes are tested. It is found that the sensitivity increases with the reduction of particle size. Particle size of 8–10 nm is desirable for fast response and recovery. As to the long-term stability, sensors free from any additive fabricated by particle size smaller than 20 nm, drift more or less. However, when Pd and some other additives were added, sensor made of 10-nm particles has improved stability. This Pd-doped ultrafine particle (UFP) sensor exhibits high sensitivity and selectivity to CO, H2 and CH4 at heating currents of 30, 100 and 160 mA (30°C, 120°C, 300°C), respectively.