N dopants triggered new active sites and fast charge transfer in MoS₂ nanosheets for full Response-Recovery NO₂ detection at room temperature

The slow response and incomplete recovery are primary bottlenecks for the sensing performance of 2D transition-metal dichalcogenides (TMDs) at room temperature, which hinders their development for state-of-the-art gas sensors. Herein, we engineered N doped p-type MoS₂ against its native n-type propensity to enable a rapid room-temperature response/recovery detection of NO₂. Compared to pristine n-type MoS₂ showing typical slow response and no recovery (1544 s/-), the prepared N-doped MoS₂ sensor exhibits a fast response/recovery (22/109 s) toward 10 ppm NO₂ at room temperature. In addition, the N dopants endow MoS₂ with a sensing response of 28% to 10 ppm NO₂, ppb-level of detection limit (125 ppb), excellent selectivity, good repeatability, and humidity resistance. We underline the fast response/recovery mechanism of N-doped MoS₂ to be the N dopants triggered synergistic effect of new active sites and fast charge transfer based on density functional theory calculation and Hall-Effect measurement. We hope this result may shed a new light on the development of TMDs-based sensing materials aiming at improving their room-temperature response/recovery performance.