Mechanism of Fast NO Response in a WO[sub.3]-Nanorod-Based Gas Sensor

The development of fast and reliable gas sensors is a pressing and growing problem for environmental monitoring due to the presence of pollutants in the atmosphere. Among all gases, particular attention is devoted to NO, which can cause serious health problems. WO[sub.3] nanorods represent promising candidates for this purpose due to their high electrical stability and low cost of production. Here, the hydrothermal synthesis of WO[sub.3] nanorods is reported, in addition to the realization of a chemo-resistive NO sensor. NO-sensing tests were performed at different temperatures (250–400 °C) and under different gas concentrations (250–2500 ppm), and NO response and recovery curves were also modeled by using the Langmuir adsorption theory by highlighting the NO-sensing mechanism of the WO[sub.3] nanorods. An interaction occurred at the surface between NO and the adsorbed oxygen ions, thus clarifying the NO-reducing behavior. The fast response and recovery times open the route for the development of fast NO sensors based on WO[sub.3] .