Room Temperature Sub-ppm NO2 Gas Sensor Based on Ag/SnS2 Heterojunction Driven by Visible Light

Abstract

As industrial waste gas, nitrogen dioxide (NO2) is a serious hazard to air pollution and human health, and there is a pressing demand for developing high-performance NO2 gas sensors. Tin disulfide (SnS2), a representative two-dimensional metal sulfide characterized by a significant specific surface area, a suitable electron band gap, and an easily tunable layered structure, shows a broad application prospect in gas sensing applications. Nevertheless, SnS2-based gas sensors suffer from poor sensitivity, which seriously hinders their application in room temperature gas sensing. In this study, Ag/SnS2 heterojunction nanomaterials were synthesized by an in situ reduction approach. The findings reveals that the gas-sensitive response of the Ag/SnS2 nanocomposites at room temperature under visible light irradiation can achieve 10.5 to 1 ppm NO2, with a detection limit as low as 200 ppb, which realizes the room-temperature detection of Sub-ppm NO2. Meanwhile, the sensor exhibits good selectivity, reproducibility (cyclic stability > 95%). The improved gas sensitivity of the Ag/SnS2 sensor can be due to the synergistic effect of the carrier separation at the Ag/SnS2 Schottky junction and the localized surface plasmon resonance (LSPR) of Ag nanoparticles. The LSPR effect significantly enhances light absorption and surface-active site density, facilitating trace NO2 detection at room temperature. This study provides the foundation for the subsequent development of room temperature layered metal sulfide gas sensors.