3D MoS ₂2 Aerogel for Ultrasensitive NO ₂2 Detection and Its Tunable Sensing Behavior

摘要

> A high‐performance NO ₂ sensor based on the 3D MoS ₂ aerogel is presented. Compared to single‐ or few‐layer MoS ₂ , 3D assemblies of 2D MoS ₂ provide more surface area per footprint with a simple and scalable synthesis. Integration of the 3D MoS ₂ aerogel on a low‐power microheater platform is demonstrated, and the sensing behavior of the 3D MoS ₂ aerogel is investigated. A two‐step sulfurization treatment is developed to obtain a high‐quality MoS ₂ aerogel with strong sensing performance. The aerogel exhibits low detection limit (50 ppb) toward NO ₂ at room temperature, while after the two‐step sulfurization treatment, it also exhibits fast response and recovery at low heater temperature of 200 °C, with no decrease in sensitivity. The observed p‐type sensing behavior of MoS ₂ aerogel is investigated and identified as being controlled by the defect state (as probed by the S:Mo ratio). It is demonstrated that annealing in a hydrogen environment changes the defect state of the MoS ₂ aerogel by creating more sulfur vacancies; concomitantly, a transition from p‐type sensing behavior to n‐type sensing is observed.