Tailoring the structural and microstructural properties of nanosized tantalum oxide for high temperature electrochemical gas sensors

Ta ₂O ₅ nanopowders to be used as sensing electrodes in high temperature electrochemical gas sensors for hydrocarbons detection were synthesized using a sol-gel method and their structural and microstructural properties were investigated. The as-synthesized powders were heated at different temperatures in the range 250-1000 °C and characterized by TG-DTA, XRD, SEM, TEM and FT-IR. This investigation allowed to identify the correct thermal treatments to achieve the microstructural, textural and functional stability of materials working at high temperature, preserving their nanometric grain size. Planar sensors fabricated by using Ta ₂O ₅ powders treated at 750 °C showed promising results for the selective detection of propylene at high temperature (700 °C). The good stability of the sensing response after gas exposure at high temperature was correlated to the stable microstructure the electrodes. Thus, Ta ₂O ₅ powders seems good candidate as sensing electrode for sensors for automotive exhausts monitoring.