Moisture-Resistant and Highly Selective NH 3 Sensor Based on CdS/WS 2 Composite Heterojunction.

This study reports the synthesis of CdS/WS 2 composites via a green and ultra-low-cost hydrothermal method. By controlling the relative mass ratio between WS 2 and CdS, an n-n type CdS/WS 2 heterostructure, with excellent NH 3 gas-sensitive properties, was developed and investigated at room temperature. Compared with pristine WS 2 and CdS, the CdS/WS 2 -40%wt composite exhibited excellent selectivity of more than 4 orders of magnitude for sensing NH 3 , a very short recovery time of 3 s, and ultrahigh selectivity at room temperature. The large specific surface area of the CdS/WS 2 composite increased the active sites for the gas-sensitive reaction. Additionally, the 2D morphology of CdS/WS 2 and the heterojunction formed between WS 2 and CdS contributed to the improved performance. Anti-humidity interference tests showed that the CdS/WS 2 sample remained stable under real-time monitoring of NH 3 at different ambient humidity values. This study paves the way for designing high-performance gas sensors operating at room temperature.