Preparation of WO3nanoplatelet-based microspheres and their NO2gas-sensing properties

Abstract

Microspheres consisting of WO3nanoplatelets were prepared by a simple polyol process using tungsten chloride, poly- (vinylpyrrolidone) (PVP), and ethylene glycol. The microsphere sizes could be easily controlled by the appropriate adjustment of the molecular weight of the added PVP from 3500 to 1300000. The microspheres prepared by using PVP with a molecular weight of 1300000 had average diameters of about 877nm and consisted of nanoplatelets that were ~500nm long by 30nm wide. The gas-sensing properties of the WO3microspheres were investigated by exposure to 50 ppb to 1ppm NO2. The sensor element constructed with microspheres composed of the PVP with a molecular weight of 1300000 showed a higher sensor response to NO2gas than the others, because the nanoplatelets had smaller particle sizes and larger specific surface areas.