Ultrasensitive NO2 sensor based on In2O3 nanocubes/SnS2 nanoflowers hetero composites

The development of highly efficient nitrogen dioxide (NO₂) sensors with excellent performance and low concentration detection capabilities is urgently needed for environmental monitoring and human health protection. In this study, In₂O₃ nanocubes and SnS₂ nanoflower composites were assembled by hydrothermal method, achieving ultrasensitive detection of NO₂. The gas sensing test results indicate that the 7 wt% In₂O₃/SnS₂ sensor exhibits significant NO₂ gas sensing performance, with a high response value of 15.61 for 5 ppm NO₂, which is approximately 5 times that of the SnS₂ sensor (3.12). Additionally, the 7 wt% In₂O₃/SnS₂ sensor demonstrates good response and recovery times (34 and 65 s, respectively), along with excellent cross-selectivity, humidity resistance, repeatability, and long-term stability. Moreover, this sensor achieves ppb-level detection of NO₂. The excellent gas sensing performance is attributed to the 7 wt% In₂O₃/SnS₂ flower-like hierarchical structure owing to a large surface area and abundant active sites, as well as the n-n heterojunction that improves carrier mobility and enhances the gas sensing performance. The adsorption energy, charge transfer, and density of states of In₂O₃/SnS₂ adsorbed NO₂ system were analyzed using density functional theory (DFT) to explore the mechanism of gas sensing enhancement. Thus, the In₂O₃/SnS₂ sensor paves the way for future real-time and rapid detection of NO₂ gas.