Triggered new active sites and fast charge transfer in TiO2@N-doped MoS2 for ppb-level ethanol detection at low temperatures via heterogeneous interface construction

As a flammable and volatile liquid, ethanol is also a marker of diabetes in children that can be rapidly detected by gas sensors based on metal oxide semiconductors. However, reducing the operating temperature and achieving high response at ultra-low concentrations remain urgent tasks. In this study, N-doped p-type MoS 2 and MIL-125(Ti) -derived n-type TiO 2 were selected to construct p-n heterostructure with rich active sites and fast carrier transport, which further optimized the detection limit of ethanol gas at lower operating temperature. Compared with pure TiO 2 , the TiO 2 @N-doped MoS 2 composite with a MoS 2 mass ratio of 60 wt% exhibits significantly improved gas sensing properties for ethanol, including lower operating temperature (160 °C), higher response value (R a /R g  = 9.229 at 100 ppm), and ppb-level detection limit (1.702 at 100 ppb), as well as good repeatability and stability. These improvements in sensing performance could be mainly attributed to the electronic effects of MoS 2 , the synergistic effect of p-n junctions, and the strong adsorption energy of TiO 2 @N-doped MoS 2 composites on the ethanol gas. This work suggests that the prepared TiO 2 @N-doped MoS 2 composites are promising materials for the highly efficient detection of ethanol.