Gas sensing characteristics of polycrystalline SnO2 nanowires prepared by polyol method

Sn-precursor nanowires (NWs) were prepared by refluxing a solution containing tin oxalate (SnC2O4) and ethylene glycol. The precursor NWs were heat-treated at 600 °C, which successfully transformed them into SnO2 NWs without undergoing any morphological change. The morphology of the SnO2 NWs could be manipulated either by controlling the SnC2O4 concentration or by adding easily reducible noble metal salts, such as PdCl3, AgNO3 or RuCl3·H2O. The thicker and shorter SnO2 NWs, which resulted from the use of a high SnC2O4 concentration during the preparation, showed lower gas sensitivity due to their decreased gas sensing surface area. The addition of catalytically active Pd, Ag, or Ru not only changed the gas sensitivity but also significantly shortened the gas recovery times. The gas sensing characteristics of the SnO2 NWs were related to the NW morphology and, when applicable, the catalyst used.