Sulfur Vacancies Enable Reversible NH 3 Chemisorption on Monolayer MoS 2 for Ultrasensitive Room Temperature Sensing
Lun Tan, Wei Li, Ang Li, Zhao Wang, Peng Wu, Zhen Zhang, Lei Jiang, Chong Li, Jinghao Lei, Yongming Hu, Daliang Zhang, Haoshuang Gu, Xiaodong HanABSTRACT
Sensitive ammonia (NH 3 ) detection at room temperature (RT) is essential for environmental monitoring, industrial safety, and emerging energy technologies. However, developed semiconductor sensors often suffer from insufficient NH 3 response magnitude, slow response kinetics, and a requirement for elevated temperatures. In this work, we propose a controllable surface Sulfur‐vacancy (V S ) induced physisorption to reversible RT‐chemisorption transition for NH 3 on monolayer molybdenum disulfide (MoS 2 ). This transition facilitates the extensive formation of N─Mo bonds, narrows the band gap of MoS 2 substantially, and achieves highly sensitive NH 3 detection accordingly. Consequently, an optimized vacancy density of 8.0 at.% enables RT‐NH 3 sensing with a theoretical detection limit of 2.2 ppb, a wide dynamic range up to 10000 ppm, a minimum response time less than 2 s, and a remarkable selectivity ratio of 12. Benefiting from large surface and enhanced charge transfer, our RT‐ NH 3 prototype portable detector can deliver a prominent response of 23.7 with response time of 12 s toward 50 ppm NH 3 , and reversible recovery under 40% relative humidity (RH). These results establish rational RT‐chemisorption enabled molecular recognition as a route to superior performance RT‐NH 3 sensing in two‐dimensional monolayered materials.