Sensitization of TiO2/SnO2 nanocomposites for gas detection

TiO2/SnO2 nanocomposites prepared by mechanical mixing of nanopowders are proposed as potential candidates for hydrogen sensing. Full compositional range from 100 mol % TiO2 to 100 mol % SnO2 has been covered and characterized by X-ray diffraction, XRD; Scanning Electron Microscopy, SEM; Transmission Electron Microscopy, TEM; Brunauer–Emmett–Teller, BET adsorption isotherms and impedance spectroscopy, IS. High and reproducible responses in reaction with hydrogen at a relatively low temperature have been obtained. Significant influence of humidity on the impedance spectra has been observed. Nanocomposite of 50 mol % TiO2/50 mol % SnO2 shows the highest response in interaction with hydrogen over the entire range of operating temperatures from 225 °C to 400 °C. Sensitization of TiO2/SnO2 is due to the formation of contact potential at grain boundaries that results in the charge transfer from SnO2 to TiO2 and facilitates oxygen adsorption.