Sensitization of Gas Sensing Properties in TiO2/SnO2 Nanocomposites

TiO2/SnO2 composites prepared by mechanical mixing of TiO2 and SnO2 nanopowders over a full compositional range from 100 mol% TiO2 to 100 mol% SnO2 are characterized by BET adsorption, isotherms method, X-ray diffraction, Scanning Electron Microscopy, SEM, Transmission Electron Microscopy, TEM, spectrophotometry and impedance spectroscopy, IS. Gas sensors made of these nanopowders show high and reproducible responses in reaction with hydrogen at a relatively low temperature, not exceeding 400 °C. Remarkable increase in the sensor sensitivity accompanies mixing of SnO2 nanopowder with a small amount (2 mol%) of TiO2. This effect can be accounted for by an enhanced oxygen preadsorption on SnO2 grains due to the electron transfer from TiO2 to SnO2.