Ag-Modified SnS₂/SnO₂ Nanoheterojunctionsfor Low-Temperature NO₂ Sensing

Abstract

Realizing low-temperature detection of NO₂ is crucial to protecting the environment and human health. In this study, SnS₂/SnO₂ hexagonal nanosheets with an average size of 630 nm were synthesized by a two-step process. Subsequently, Ag nanoparticles were modified on the surface of SnS₂/SnO₂ to form Ag-modified SnS₂/SnO₂ nanoheterojunctions. Compared to SnS₂ and SnS₂/SnO₂ sensors, Ag/SnS₂/SnO₂-based sensors have better gas-sensing performance at the optimum operating temperature of 100 °C, including higher response, better stability, and excellent selectivity to NO₂. The response value of the Ag/SnS₂/SnO₂ sensor to 7 ppm of NO₂ at 100 °C is 56.4, which is four times higher than that of the SnS₂ sensor. The outstanding NO₂ sensing properties of the Ag/SnS₂/SnO₂ can be due to the combination of Ag modification and the formation of the SnS₂–SnO₂ heterojunction.