Sub-ppt NH₃ detection by MoS₂@sulfur nanosheets

Novel nanostructured materials are expected to revive materials for chemiresistive sensor applications. MoS₂-based gas sensor is widely studied, however, which usually is capable of detecting gas at ppm level. Here, owing to the two-dimensional layered structure that facilitated the surface reaction, sulfur nanosheets (S-NSs) was first designed to composite with MoS₂ to improve the sensing performance. Because of the unique electronic and physical properties of S-NSs, the developed chemiresistive sensor based on MoS₂@S-NSs nanocomposite demonstrated to realize ultrasensitive detection of NH₃ at 0.1 ppt level with a response signal of 68%, and which also showed fast response and recover (9/8.7 seconds respectively) at room temperature in air. Except for the good electrical conductivity and the large adsorption site of MoS₂, the excellent sensing property of S-NSs itself made the most important contribution to this appealing high sensitivity to NH₃. Additionally, this study has also put forth comprehensive gas sensing mechanisms based on experimental results. In essence, this research offers an innovative materials system tailored for the highly efficient detection of NH₃.