Enhanced interfacial molecular interactions in WS2/ZnS heterojunctions enabling ppb-level NH3 detection at room temperature

Designing a gas sensor equipped with the ability to detect ppb-level ammonia at room temperature remains a substantial challenge. The strategy of enhancing interfacial molecular interactions via interfacial charge transfer is highly feasible for the detection of low-concentration gases. In the research, a mixed-dimensional WS 2 /ZnS heterojunction was synthesized for ammonia detection. The results show that the sensor exhibits an ultra-sensitive ammonia response. The theoretical limit of detection (LOD) for the WS 2 /ZnS sensor is 7.3 ppb NH 3 . Additionally, the sensor delivers excellent sensitivity, selectivity, and long-term stability. WS 2 /ZnS heterojunction facilitates the chemisorption and diffusion of ammonia. In-situ data and structure analysis reveal that interfacial charge transfer induces the polarization of W-S bonds, facilitating the adsorption of ammonia and the gas-sensing reaction between ammonia and oxygen anions, thereby accelerating the kinetics of the gas-sensing reaction. This work highlights the great potential for constructing a strong chemical bond polarization to improve the detection of low-concentration ammonia of WS 2 -based sensors.