High-performance room-temperature NO ₂ gas sensors enabled by 0D SnO ₂ /1D WO ₃ heterostructures for wearable applications

The sensor for nitrogen dioxide (NO₂) detection plays a crucial role in environmental monitoring and human health. However, traditional oxide-based NO₂ sensors often suffer from high operating temperatures, low sensitivity, and inherent rigidity. In this work, a high-performance, wearable NO₂ gas sensor that can work at room temperature was developed based on a nanocomposite of single-crystal tungsten oxide (WO₃) and tin dioxide (SnO₂). The results show that the fabricated SnO₂/WO₃ based sensor demonstrates superior performance to the bare WO₃ sensors. Specifically, the Sn/W-O-12 based sensor shows a remarkable response of 2.61% to 0.8 ppm NO₂ and a low detection limit of 218 ppb at room temperature. Furthermore, its response/recovery time to 0.8 ppm NO₂ is 63/38 s, respectively. The sensing device also exhibits excellent humidity resistance (80%) and long-term stability (60 days). The enhanced NO₂ sensing performance can be attributed to the formation of a heterojunction interface, achieved by the dispersion of small-sized SnO₂ particles onto WO₃ nanorods, which increases the specific surface area and facilitates charge transfer and gas molecule adsorption on the surface. Additionally, a NO₂ gas detection and alarm system was constructed to realize the real-time display and alarm functions. This work contributes to the detection of low concentrations of NO₂ at room temperature, fostering the development of wearable sensing systems.