Enhanced CO sensitivity and selectivity of gold nanoparticles-doped SnO2 sensor in presence of propane and methane

We report the effect of gold nanoparticles on the sensitivity and selectivity of SnO2-based sensors for detection of CO in the presence of methane and C3H8, a model compound representing liquid petroleum gas (LPG). 1.0 wt% Au/SnO2 powder was prepared by a co-precipitation method. The powder formed was washed, dried at 150 °C, and calcined at 300 °C for 3 h. The BET surface area of SnO2 and Au/SnO2 was measured to be 210 and 110 m2/g, corresponding to 4 and 7.5 nm loose spherical particles, respectively. Responses of the Au/SnO2 and SnO2 sensors to 40–1000 ppm CO, 0.2–1.0% C3H8 and 1.0–3.0% CH4 were studied at 170–300 °C in an automated gas sensing system. In this temperature range, the Au/SnO2 sensor is about 4–17 and 7–20 times more selective to 0.1% CO in the presence of 1.0% propane and 3.0% methane, respectively. Highly dispersed gold nanoparticles may be responsible for the enhanced sensitivity and selectivity of the Au/SnO2 sensor to CO.