Hydrogen sulfide detection by nanocrystal Pt doped TiO2-based gas sensors

Nanocrystalline (NC) materials, exhibiting a large surface area may be used as gas sensors for which a large surface effect is required ii? this study, NC TiO2 was synthesized by means of the gas-evaporation method The mean particle size of NC TiO2 under 20 mbar of oxygen/helium (I:4)was about 20 nm. The dopant, NC Pt less than 10 nm in diameter, was directly deposited onto the surface of NC TiO2 to improve the sensitivity of NC TiO2-based sensor. The highest sensitivity was detected in NC 4.3 at% Pt/TiO2 and is about 70 in 250 ppm H2S/Air at 500 degrees C and is higher than that of the pure NC TiO2 which was 47 in the same sensing conditions. This temperature is lower than that of a traditional TiO2 sensor (similar to 700 degrees C) by about 200 degrees C. The response time of NC TiO2 and NC Pt/TiO2 at 500 degrees C is less than 1 minute.