Nanocasting Synthesis of Ultrafine WO(3) Nanoparticles for Gas Sensing Applications

Ultrafine WO(3) nanoparticles were synthesized by nanocasting route, using mesoporous SiO(2) as a template. BET measurements showed a specific surface area of 700 m (2)/gr for synthesized SiO(2,) while after impregnation and template removal, this area was reduced to 43 m (2)/gr for WO3 nanoparticles. HRTEM results showed single crystalline nanoparticles with average particle size of about 5 nm possessing a monoclinic structure, which is the favorite crystal structure for gas sensing applications. Gas sensor was fabricated by deposition of WO(3) nanoparticles between electrodes via low frequency AC electrophoretic deposition. Gas sensing measurements showed that this material has a high sensitivity to very low concentrations of NO(2) at 250°C and 300°C.