Gas sensing properties of WO3-doped ZnO nanoparticles synthesized by flame spray pyrolysis

The flame-made (5/5) pure ZnO and WO₃-doped ZnO nanoparticles containing 0.25, 0.50, and 0.75 mol% of WO₃ were successfully synthesized by flame spray pyrolysis (FSP). These materials were studied for NO₂, CO and H₂ gas sensing at different gas concentrations and operating temperatures ranging from 300-400°C in dry air. The crystalline phase, morphology and size of the nanoparticles were characterized by XRD, BET, TEM, SEM and EDS in order to correlate physical properties with gas sensing performance. The gas-sensing results showed that WO₃ doping significantly enhanced NO₂ gas-sensing performance of ZnO nanoparticles. In addition, 0.5 mol% is found to be an optimal WO₃ concentration which gives the highest sensitivity towards NO₂.