Synergetic Phase Modulation and N-Doping of MoS for Highly Sensitive Flexible NO Sensors.

Molybdenum disulfide (MoS) is a promising electronic material owing to its excellent electrochemical features, high carrier mobility at room temperature, and widely tunable electronic properties. Here, through precursor engineering and post-treatments to tailor their phase and doping, electronic characteristics of MoS are significantly modified. It is found that 2H semiconductor phase with nitrogen doping (N-doping) in flexible gas sensors constructed with Ag electrodes exhibits the highest sensitivity of ≈2500% toward 10 ppm of NO. This sensitivity is ≈17- and 417-folds higher than that of 2H MoS without N-doping, and mixed phases with metallic 1T and semiconductor 2H phase, respectively. Comprehensive experimental investigations reveal mechanisms underlying this record sensitivity, that is, the use of N-doped 2H MoS sensors not only significantly suppresses dark current but also effectively enhances electron transfer to NO molecules. Moreover, density function theory calculations underpin the experimental results, confirming that NH molecules from the precursor solution not only promote phase transition but also enable N-doping during post-treatments, thus boosting sensing capability. This work, for the first time, reveals the synergistic effect of phase modulation and N-doping of MoS, which can be readily used in other flexible electronic applications, advancing MoS-based electronics to a new stage.