Enhanced Gas Sensing Characteristics of Ag2O-Functionalized Networked In2O3 Nanowires

Abstract

We have fabricated Ag2O-functionalized In2O3 nanowires, in which the NO2 gas sensing properties are enhanced. To achieve the functionalization, the core In2O3 nanowires were sputter-deposited with the Ag shell layer, which turned out to be composed of cubic Ag particles. Subsequent thermal annealing changed the Ag nanoparticles to cubic nanoparticles with a cubic Ag2O phase. In spite of shell-coating and subsequent annealing, scanning electron microscopy images revealed that the products consisted of one-dimensional nanowires. In a NO2 gas sensing test, the sensitivity of the Ag2O-functionalized sensor was lower than that of the nonfunctionalized sensor, presumably owing to the significant volume of the depletion region in the Ag2O-In2O3 interface. However, the Ag2O-functionalized In2O3 nanowires exhibited exceptionally fast response and recovery compared with bare In2O3 nanowires. We suggest that not only the catalytic effect but also the spillover effect of Ag2O nanoparticles is mainly responsible for the observed enhancement of sensing capabilities in terms of response/recovery time.