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.