Room-temperature ppb-level NO2 sensitivity of three-dimensional ordered macroporous Au-loaded SnO2 under intermittent UV light irradiation

Abstract

Metal oxide gas sensors operated at room temperature are highly desirable from the point of view of energy conservation. However, they typically suffer from a long recovery time and a low response to the target gas. In this work, we demonstrate the ultrahigh room-temperature ppb-level NO2 sensitivity of three-dimensional ordered macroporous Au-loaded SnO2 under intermittent UV light irradiation. Fabricated with a template of polystyrene opal crystal, the inverse opal of Au/SnO2 is assembled in an FCC structure, with finely dispersed Au nanoparticles anchored on the interconnected walls of SnO2. The decoration of Au nanoparticles improves the NO2 response of SnO2 under both continuous and intermittent UV irradiation due to the spillover effect of Au. Significantly improved response toward NO2 has been achieved under intermittent UV irradiation. The sensing mechanism responsible for the ultrahigh response toward NO2 has been elaborated.