tailieunhanh - Báo cáo hóa học: "Nanocasting Synthesis of Ultrafine WO3 Nanoparticles for Gas Sensing Applications"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Nanocasting Synthesis of Ultrafine WO3 Nanoparticles for Gas Sensing Applications | Nanoscale Res Lett 2010 5 370-373 DOI s11671-009-9490-8 NANO EXPRESS Nanocasting Synthesis of Ultrafine WO3 Nanoparticles for Gas Sensing Applications Elham Kamali Heidari Ehsan Marzbanrad Cyrus Zamani Babak Raissi Received 15 September 2009 Accepted 1 November 2009 Published online 21 November 2009 to the authors 2009 Abstract Ultrafine WO3 nanoparticles were synthesized by nanocasting route using mesoporous SiO2 as a template. BET measurements showed a specific surface area of 700 m2 gr for synthesized SiO2 while after impregnation and template removal this area was reduced to 43 m2 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 WO3 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 NO2 at 250 C and 300 C. Keywords WO3 Nanocasting Low frequency AC electrophoretic deposition NO2 gas sensor Introduction Semiconductor gas sensors offer good advantages with respect to other gas sensor devices due to their simple implementation low cost and good reliability for real-time control systems 1-3 . Among them ZnO WO3 and SnO2 have widely been studied 4 . Tungsten oxide WO3 is a wide band gap n-type semiconductor that has interesting E. Kamali Heidari E. Marzbanrad B. Raissi Materials and Energy Research Center . Box 14155-4777 Tehran Iran C. Zamani El ME2 Departament d Electronica Universitat de Barcelona Marti i Franques 1 08028 Barcelona Spain e-mail czamani@ physical and chemical properties 5-9 . WO3 is a good photochromic electrochromic thermochromic and catalytic material 9-12 . Gas sensing is a surface effect. As gas adsorption occurs at surface level an increase in the active surface area of the .