NO2 sensing properties of WO3 varistor-type gas sensor

NO2 sensing properties of pure WO3 ceramics based on the gas sensitive nonlinear current–voltage (I–V) characteristics have been investigated. Experimental results show that WO3 ceramics exhibit nonlinear I–V characteristics and breakdown voltage shift to a high electric field upon exposure to NO2, thus exhibiting NO2 sensitivity, and the operating temperatures and voltages are relatively lower than the previous reported varistor-type gas sensors. The mechanism of gas sensitive nonlinear I–V characteristics has been explained by the alternations of the potential barriers at the grain boundaries. The present results demonstrate that WO3 can be used as a new varistor-type gas sensor material.