Gas-sensing properties of catalytically modified WO3 with copper and vanadium for NH3 detection

Ammonia gas detection by pure and catalytically modified WO₃-based gas sensors was analyzed. Sensor response of pure tungsten oxide to NH₃ was unsatisfactory, probably due to the unselective oxidation of ammonia into NO_x. Copper and vanadium were introduced in different concentrations and the resulting material was annealed at different temperatures in order to improve the sensing properties for NH₃ detection. The introduction of Cu and V as catalytic additives improved the sensor response to NH₃. Possible reaction mechanisms of NH₃ over these materials are discussed. Sensor responses to other gases like NO₂ or CO and interference of humidity on ammonia detection were also analyzed so as to choose the best sensing element.