Synthesis, Characterization and Sensing Behavior of WO₃ Nanocrystalline Powder for Toluene Vapor

Tungsten oxide (WO₃) nanocrystalline powder was successfully synthesized by direct precipitation technique starting from sodium tungstate dehydrate (Na₂WO₄·2H₂O) as precursor at 80°C for 48 h. The morphological characteristics, distribution, and crystallite size of WO₃ nanocrystalline powder were analysed by transmission electron microscopy, X-ray diffraction, and the Fourier transform infrared spectroscopy. According to transmission electron microscopy results, the mean particle size of WO₃ nanocrystalline powder was approximately determined as 41.7 nm. The gas sensing performance of WO₃ nanocrystalline powder for saturated toluene vapor was measured by two probe resistivity unit in a closed vessel at room temperature. In addition, WO₃ nanocrystalline powder was able to respond the lowest concentration of 500 ppm. The results showed that the sample exhibited high sensitivity (93%) and good response reproducibility (0.93+5.5%) for toluene vapor.