Preparation and gas sensing properties of undoped and Pd-doped TiO2 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 H2 sensors.