Preparation and gas sensing properties of undoped and Pd-doped TiO ₂ nanowires

Titanium dioxide (TiO₂) nanowires with a rutile structure were prepared by thermal evaporation method using Ti metal powder as a raw material. The major factor that influenced the morphology was the furnace temperature. The uniform nanowires can be prepared at the furnace temperature of 1200 C, which were approximately 50-220 nm in diameter and several tens of micrometers in length. Sensors were fabricated by pouring a few drops of product suspended ethanol onto oxidized Si substrates equipped with a pair of interdigitated Pt electrodes and H₂ gas sensing properties were investigated. Both undoped and Pd-doped TiO₂ nanowire gas sensors showed the highest response at 100 C. Comparing with undoped nanowire sensor, Pd-doped nanowire sensor exhibited much higher response and rapider response/recover characteristic to H₂ gas. The results demonstrated that Pd-doped TiO₂ nanowires can be used to fabricate high performance H ₂ sensors.