Growth of SnO2 nanowire arrays by ultrasonic spray pyrolysis and their gas sensing performance

The direct synthesis of tin dioxide (SnO2) nanowire arrays on a glass substrate by using an ultrasonic spray pyrolysis method combined with sintering is demonstrated. The products obtained are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM) and high-resolution TEM. The results show that the SnO2 nanowire arrays consist of single crystalline nanowires, each with a diameter of 50-70 nm and a length of 5-7 mm. There are two different nanowire growth directions because of the oxygen defect growth. The mechanism of the formation and growth of SnO2 nanowire arrays was investigated. A platform gas sensor based on these arrays was fabricated. The sensor exhibits better sensitivity to and selectivity for NO2 than do SnO2 nanoparticles. The gas sensing mechanism is also discussed.