WO3 and WO3-SnO2 Composite-Based Sensors for Low-Temperature Detection of NO2 Gas

Air pollution, along with climate change, poses significant risks to human health. One of the major contributors to air pollution, particularly in urban areas, is nitrogen dioxide (NO₂). Continuous real-time monitoring of NO₂ is necessary for the protection of human health and the environment. Currently, efforts are concentrated across the globe toward the development of compact NO₂ sensors that exhibit higher responses at lower operating temperatures. In the present work, conductometric gas sensors based on tungsten trioxide (WO₃), tin oxide (SnO₂), and tin oxide–tungsten trioxide (WO₃-SnO₂) composites have been developed using the chemical solution deposition (CSD) technique for NO₂ detection. The investigation of the sensing response was conducted over a range of temperatures, spanning from 30°C to 180°C towards 10 ppm of NO₂. The pristine WO₃ sensor showed a maximum response of ~ 535 at 150°C with a response time of 21 s and recovery time of 126 s, whereas the WO₃-SnO₂ composite sensor showed a maximum response of ~ 209 at a relatively lower temperature of 120°C with a response time of 37 s and recovery time of 135 s. The composite sensor thus shows the potential for the realization of an efficient NO₂ sensor at a lower operating temperature.