Synergism of Edge Effect and Interlayer Engineering of VS₂ on CNFs for Rapid and Precise NO₂ 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 NO₂ sensor based on an expanded VS₂ (VS₂-E)/carbon nanofibers (CNFs) composite (abbreviated as VS₂-E-C) with ultrafast response/recovery at a low-loss state is reported. In particular, the impact of the CNF content on the NO₂-sensing performance of VS₂-E-C was thoroughly explored. Expanded VS₂ nanosheets were grafted onto the surface of hollow CNFs, and the combination boosted the charge transport, exposing abundant active edges of VS₂, which enhanced the adsorption of NO₂ efficiently. The activity of the VS₂ edge is further confirmed by stronger NO₂ adsorption with a more negative adsorption energy (-3.42 eV) and greater than the basal VS₂ surface (-1.26 eV). Moreover, the exposure of rich edges induced the emergence of the expanded interlayers, which promoted the adsorption/desorption of NO₂ and the interaction of gas molecules within VS₂-E-C. The synergism of edge effect and interlayer engineering confers the VS₂-E-C3 sensor with ultrafast response/recovery speed (9/10 s) at 60 °C, high sensitivity (∼2.50 to 15 ppm NO₂), good selectivity/stability, and a low detection limit of 23 ppb. The excellent "4S" functions indicate the promising prospect of the VS₂-E-C3 sensor for fast and precise NO₂ detection at low-loss condition.