Ultrasensitive NO₂ Gas Sensors Based on Layered α‐MoO₃ Nanoribbons

Abstract The detection and monitoring of nitrogen dioxide (NO₂) plays a vital role in the environmental, healthcare, farming, and industrial sectors. However, the development of NO₂ gas sensors with simultaneously high sensitivity, reversibility, low detection limit, and excellent selectivity remains challenging. In this work, an ultrasensitive NO₂ gas sensor with superb selectivity and reversibility is demonstrated based on α‐phase molybdenum trioxide (α‐MoO₃). Nanoribbons of α‐MoO₃ are synthesized via vapor phase transport (VPT) and systematically characterized using a combination of advanced characterization probes. At an optimal operating temperature of 125 °C, the α‐MoO₃‐based sensor shows a very high sensitivity toward NO₂ with a detection limit as low as 24 ppb, while also exhibiting excellent selectivity and reversibility. Such impressive performance originates from the layered nature of the α‐MoO₃ nanoribbons as well as the hierarchical assembly of the nanoribbons as the sensing layer. The study demonstrates a facile sensing platform based on α‐MoO₃ for ultrasensitive and selective NO₂ gas sensing.