Ethanol Gas Sensors With Nanocomposite of Nickel Oxide and Tungsten Oxide

Different nanostructures of tungsten oxide (WO
₃
) can be hydrothermally synthesized by controlling the pH value through adding HCl solution. WO
₃
has a square plate-like structure when the mixture solution has a pH value of 1.0. At this pH, WO
₃
nanoplates are dispersed and did not formed clusters. Porous nickel oxide (NiO) spheres are also hydrothermally synthesized for decoration on the surface of WO
₃
nanoplates. Holes on the NiO spheres increase the surface area of the material and enhance the sensing performances of the sensor. By combining these two materials, the sensor with p-n-n junction is sensitive to ethanol and has a high sensitivity of 155%. The response and recovery times are also fast with good sensitivity and selectivity. It has a high potential for applying to ethanol sensing in industrial and medical areas.