Novel hexagonal WO3 nanopowder with metal decorated carbon nanotubes as NO2 gas sensor

In this work, hexagonal tungsten oxide (hex-WO3) nanopowders were prepared by acidic precipitation from a sodium tungstate solution. TEM analysis of nanopowders showed that the average size of the hexagonal nanoparticles was 50–100 nm. Novel hybrid composites were fabricated by embedding a low amount of carbon nanotubes into the hex-WO3 matrix. Metallic nanoclusters (Ag, Au) were added to the carbon nanotubes for improving the gas sensing properties of the films. The addition of MWCNTs lowered the temperature range of sensitivity of the hex-WO3 nanocomposites to NO2 hazardous gas. In comparison, the sensitivity of hex-WO3 to NO2 was in the temperature range between 150 °C and 250 °C, while the hex-WO3/MWCNTs composites were sensitive to NO2 gas at room temperature.