Sensitivity enhancemenet in SnO2 based gas sensors by surface decoration with platinum nanoparticles

Gas sensitivity and electronic properties of pure SnO₂ thin films as well as those surface decorated with platinum nanoparticles were examined in different atmospheres. The SnO₂ films were deposited onto SiO₂ substrates by an ultrasonic spray pyrolysis (USP) technique. Then, in a separate process, Pt nanoparticles were electrochemically deposited on their surfaces. Metallic contacts were provided by silver paste printing. The sensors were examined in clean air and 500 ppm ethanol (C₂H₅OH) contaminated atmospheres at different operation temperatures in the 275 to 350 °C range. The Pt/SnO₂ sensors proved to be 4 times more sensitive. Moreover, the maximum sensitivity of the Pt-decorated device occurred at a lower operating temperature. These observations are attributed to the catalytic activity of the Pt nanoparticles.