Nanocasting synthesis of ultrafine WO 3 nanoparticles for gas sensing applications

Abstract

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. © 2009 to the authors.