A novel ppm level ethanol sensor based on La loaded ITO impregnated with Pd and Sb additives.

• Using a unique gel calcination procedure 4 at% La loaded ITO nanopowder prepared. • Its sensing response was ~65% in 10 ppm ethanol but base resistance quite high. • 1wt% Pd & 0.5 wt% Sb loading enhanced response ~20% with acceptable resistance. • Stable and able to detect ~1 ppm of ethanol with fast response and recovery time. • Reproducible sensing performance with minimum interference. The present work reports on a novel resistive ppm level ethanol sensor, prepared from nanocrystalline lanthanum loaded indium tin oxide (ITO) impregnated with palladium and antimony additives. A simple unique gel calcination process was adapted to synthesize the nanocomposite powders from their water based precursor salts. This was followed by detailed material characterizations through X-ray diffractometer, FESEM, TEM, EDX and XPS analyses. Fabricated Taguchi type sensor with an optimum concentration of Pd exhibited an excellent sensing performance towards a wide concentration range of (1–100 ppm) ethanol vapour. The sensor showed ~87% sensing response for 10 ppm ethanol vapour at an operating temperature of 300 °C. Even at 1 ppm concentration, ~53% response was observed with fast response and recovery time. The sensing action has been elucidated as the catalytic oxidation of ethanol to carbon di oxide over the La loaded ITO surface layer that resulted in electron transfer to the indium tin oxide site. In addition, synergistic effect of palladium and antimony enhanced the sensing performance as well as reduced the base resistance of the sensor by chemical/electronic sensitization and increasing carrier ion concentration respectively. Comparatively low resistance, negligible cross sensitivity, quick response/recovery time and good long term stability makes the sensor suitable for deployment in practical applications. [ABSTRACT FROM AUTHOR]