Role of the heterojunctions in In2O3-composite SnO2 nanorod sensors and their remarkable gas-sensing performance for NOx at room temperature

Abstract

Establishing heterostructures, as a good strategy to improve gas sensing performance, has been studied extensively. In this research, In₂O₃-composite SnO₂ nanorod (ICTOs) heterostructures have been prepared via electrospinning, followed by calcination. It is found that In₂O₃ can improve the carrier density and oxygen deficiency of SnO₂. In particular, the 3ICTO (Sn : In atom ratio of 25 : 0.3) nanorods with special particle distributions show an excellent sensing response towards different concentrations of NO_x at room temperature. The highest sensing response is up to 8.98 for 100 ppm NO_x with a fast response time of 4.67 s, which is over 11 times higher than that of pristine SnO₂ nanorods at room temperature and the lowest detection limit is down to 0.1 ppm. More significantly, it presents good stability after 30 days for NO_x of low concentration (0.1 ppm and 0.5 ppm). In addition, the rational band structure model combined with the surface depletion model which describe the NO_x gas sensing mechanism of 3ICTO are presented. The 3ICTO nanorods may be promising in the application of gas sensors.