Hierarchical SnS2/SnO2 nanoheterojunctions with increased active-sites and charge transfer for ultrasensitive NO2 detection

Abstract

SnS₂ nanosheets with unique properties are excellent candidate materials for fabricating high-performance NO₂ gas sensors. However, serious restacking and aggregation during sensor fabrication have greatly impacted the sensing response. In this study, flower-like hierarchical SnS₂ was prepared by a simple microwave method and partially thermally oxidized to form hierarchical SnS₂/SnO₂ nanocomposites to further improve the sensing performance at low operating temperature. The fabricated SnS₂/SnO₂ sensor exhibited ultrahigh response (resistance ratio = 51.1) toward 1 ppm NO₂ at 100 °C, roughly 10.2 times higher than that of pure SnS₂ nanoflowers. The excellent and enhanced NO₂ sensing performances of hierarchical SnS₂/SnO₂ nanocomposites were attributed to the novel hierarchical structure of SnS₂ and the nanoheterojunction between SnS₂ and the ultrafine SnO₂ nanoparticles. The SnS₂/SnO₂ sensors also exhibited excellent selectivity and reliable repeatability. The simple fabrication of high performance sensing materials may facilitate the large-scale production of NO₂ gas sensors.