Visible light assisted room-temperature NO2 gas sensor based on hollow SnO2@SnS2 nanostructures

SnS 2 is a promising candidate for NO 2 sensing applications due to its suitable band gap and large electronegativity. However, SnS 2 based gas sensors are still restricted to detect NO 2 gas at room temperature due to their giant resistance and poor recovery. Here, we report hollow SnO 2 @SnS 2 nanostructures prepared by a one-step hydrothermal method. The SnO 2 @SnS 2 based sensor showed high response and good recovery to ppb-level NO 2 under visible illumination at room temperature (25 °C). The superior sensing performance of the SnO 2 @SnS 2 sensor was attributed to the hollow porous heterojunction structure beneficial for gas diffusion, as well as visible light assistant facilitating charge transfer and gas desorption. This work systematically studied the influence of oxygen concentration in background gas on the NO 2 sensing performance of the SnO 2 @SnS 2 sensor, and proposed a physical adsorption model for the NO 2 sensing mechanism of the SnO 2 @SnS 2 sensor under visible light at room temperature. In addition, the effect of humidity on the gas sensing performance of the SnO 2 @SnS 2 sensor to different concentrations of NO 2 was also discussed.