NO₂ sensing with CdS nanowires at room temperature under green light illumination

Detection of ppb-level NO₂ gas under atmosphere is urgent to meet the requirements of the rapidly developing internet of things. Compared with traditional sensing methods, light illumination has been considered as a key approach for excellent gas sensor performance under moderate conditions. Herein, we developed a green-light-assisted gas sensor based on cadmium sulfide nanowires (CdS NWs) that has good NO₂ sensing capability at ambient temperature. The response values of NO₂ are 236% and 11% to 10 ppm and 12.5 ppb, respectively. Furthermore, the CdS NWs sensor has a high selectivity for NO₂ over a variety of interference gases, as well as good stability. The cleaning light activation and the sulfur vacancy-trapped charge behavior of CdS NWs are observed, which suggest a light-assisted sensing mechanism. These results suggest that light-induced charge separation behavior might significantly improve gas-sensing characteristics.