Doctor-bladed thick films of flame-made Pd/ZnO nanoparticles for ethanol sensing

ZnO nanoparticles doped with 0-5 mol% Pd were produced by flame spray pyrolysis (FSP) in a single step using zinc naphthenate and palladium (II) acetylacetonate as precursors dissolved in toluene/acetonitrile (80/20 vol%). The particle properties were further analyzed by XRD, BET, and HR-TEM analyses. The sensing films were produced by mixing the particles into an organic paste composed of terpineol and ethyl cellulose as a vehicle binder. The paste was doctor-bladed onto Al2O3 substrates interdigitated with Au electrodes. The gas sensing of ethanol (25-250 ppm) was studied at 400 °C in dry air. In addition, 1 mol% Pd/ZnO film showed the highest sensitivity and fastest response times (within seconds). The sensitivity increased and the response time decreased with increasing ethanol concentration.