An ultrasensitive NO 2 sensing material was fabricated using ultrafine SnO 2 nanoparticle-modified hierarchical SnS 2 nanoflowers.
SnS 2 nanosheets with unique properties are excellent candidate materials for fabricating high-performance NO 2 gas sensors. However, serious restacking and aggregation during sensor fabrication have greatly impacted the sensing response. In this study, flower-like hierarchical SnS 2 was prepared by a simple microwave method and partially thermally oxidized to form hierarchical SnS 2/SnO 2 nanocomposites to further improve the sensing performance at low operating temperature. The fabricated SnS 2/SnO 2 sensor exhibited ultrahigh response (resistance ratio = 51.1) toward 1 ppm NO 2 at 100 °C, roughly 10.2 times higher than that of pure SnS 2 nanoflowers. The excellent and enhanced NO 2 sensing performances of hierarchical SnS 2/SnO 2 nanocomposites were attributed to the novel hierarchical structure of SnS 2 and the nanoheterojunction between SnS 2 and the ultrafine SnO 2 nanoparticles. The SnS 2/SnO 2 sensors also exhibited excellent selectivity and reliable repeatability. The simple fabrication of high performance sensing materials may facilitate the large-scale production of NO 2 gas sensors.