Effect of Pt catalyst on the sensor performance of WO3 nanoflakes towards hazardous gases

Abstract

Nobel metal functionalized chemiresistive type metal-oxide sensors were fabricated and tested against hazardous gases such as acetone, ethanol, hydrogen sulfide, hydrogen cyanide and dimethyl methylphosphonate. WO3 nanoflakes (NFs) were fabricated on Al2O3 substrates by a facile hydrothermal route. 2D nanoflakes randomly aligned and uniformly covered on the substrate surface, and the thickness of the NFs were found approximately 100 nm. Then, Pt was loaded on WO3 nanoflakes by RF sputtering method. According to the sensor tests, Pt modification tremendously improved the sensor performance of nanoflakes against acetone gas in terms of sensor response, selectivity among the measured gases and operation temperature. The spillover effect of Pt increased the sensing response and the sensor was able to selectively detect acetone with 237 particle per billion (ppb) at operation temperature of 250 degrees C. Pt functionalization suppresses the sensor responses of NFs against gases (ethanol, hydrogen sulfide, hydrogen cyanide and dimethyl methylphosphonate) other than acetone. While pristine NFs sensor was able to sense these gases at low temperatures, Pt-functionalized WO3 NFs did not sense at temperatures lower than 200 degrees C by giving rise to the selectivity of the sensor against acetone.