Synergism of Edge Effect and Interlayer Engineering of VS 2 on CNFs for Rapid and Precise NO 2 Detection.

Although two-dimensional (2D) transition-metal dichalcogenides (TMDs) exhibit attractive prospects for gas-sensing applications, the rapid and precise sensing of TMDs at low loss remains challenging. Herein, a NO ₂ sensor based on an expanded VS ₂ (VS ₂ - E )/carbon nanofibers (CNFs) composite (abbreviated as VS ₂ -E-C ) with ultrafast response/recovery at a low-loss state is reported. In particular, the impact of the CNF content on the NO ₂ -sensing performance of VS ₂ -E-C was thoroughly explored. Expanded VS ₂ nanosheets were grafted onto the surface of hollow CNFs, and the combination boosted the charge transport, exposing abundant active edges of VS ₂ , which enhanced the adsorption of NO ₂ efficiently. The activity of the VS ₂ edge is further confirmed by stronger NO ₂ adsorption with a more negative adsorption energy (-3.42 eV) and greater than the basal VS ₂ surface (-1.26 eV). Moreover, the exposure of rich edges induced the emergence of the expanded interlayers, which promoted the adsorption/desorption of NO ₂ and the interaction of gas molecules within VS ₂ -E-C . The synergism of edge effect and interlayer engineering confers the VS ₂ -E-C3 sensor with ultrafast response/recovery speed (9/10 s) at 60 °C, high sensitivity (∼2.50 to 15 ppm NO ₂ ), good selectivity/stability, and a low detection limit of 23 ppb. The excellent "4S" functions indicate the promising prospect of the VS ₂ -E-C3 sensor for fast and precise NO ₂ detection at low-loss condition.