Application of V2O5/WO3/TiO2 for Resistive-Type SO2 Sensors

A study on the application of V2O5/WO3/TiO2 (VWT) as the sensitive material for resistive-type SO2 sensor was conducted, based on the fact that VWT is a well-known catalyst material for good selective catalytic nitrogen oxide reduction with a proven excellent durability in exhaust gases. The sensors fabricated in this study are planar ones with interdigitated electrodes of Au or Pt. The vanadium content of the utilized VWT is 1.5 or 3.0 wt%. The resistance of VWT decreases with an increasing SO2 concentration in the range from 20 ppm to 5,000 ppm. The best sensor response to SO2 occurs at 400 degrees C using Au electrodes. The sensor response value is independent on the amount of added vanadium but dependent on the electrode materials at 400 degrees C. These results are discussed and a sensing mechanism is discussed.