Thin-layered MoS2 nanoflakes vertically grown on SnO2 nanotubes as highly effective room-temperature NO2 gas sensor

The unique properties of heterostructure materials make them become a promising candidate for high-performance room-temperature (RT) NO2 sensing. Herein, a p-n heterojunction consisting of two-dimensional (2D) MoS2 nanoflakes vertically grown on one-dimensional (1D) SnO2 nanotubes (NTs) was fabricated via electrospinning and subsequent hydrothermal route. The sulfur edge active sites are fully exposed in the MoS2@SnO2 heterostructure due to the vertically oriented thin-layered morphology features. Moreover, the interface of p-n heterojunction provides an electronic transfer channel from SnO2 to MoS2, which enables MoS2 act as the generous electron donor involved in NO2 gas senor detection. As a result, the optimized MoS2@SnO2-2 heterostructure presents an impressive sensitivity and selectivity for NO2 gas detection at RT. The response value is 34.67 (Ra/Rg) to 100 ppm, which is 26.5 times to that of pure SnO2. It also exhibits a fast response and recovery time (2.2 s, 10.54 s), as well as a low detection limit (10 ppb) and as long as 20 weeks of stability. This simple fabrication of high-performance sensing materials may facilitate the large-scale production of RT NO2 gas sensors.