Room-temperature NO2 sensing with engineered MoSe2 via tailored exfoliation and self-assembly

Atmospheric nitrogen dioxide (NO 2 ) is a harmful air pollutant, and its reliable detection at room temperature (RT) under ambient conditions remains a significant major challenge for gas-sensing technologies. Two-dimensional transition metal dichalcogenides (TMDs), such as MoSe 2 , have attracted considerable interest for gas-sensing applications due to their high surface area, unique electronic properties and narrow bandgap. However, the lack of scalable, cost-effective, and reproducible synthesis and film fabrication methods for TMDs significantly limits their practical deployment as gas sensors. In this work, we report a tailored liquid-phase shear (LPSE) exfoliation method combined with an interfacial self-assembly approach to produce MoSe 2 nanosheets (2–5 layers) with high crystalline quality and narrow lateral size distribution (70–110 nm). Highly stacked, interconnected and continuous MoSe 2 ultrathin films (∼40 nm) were successfully fabricated via controlled interfacial self-assembly approach. The resulting MoSe 2 -based chemiresistive sensor exhibits high response toward NO 2 (17.5% at 100 ppb), along with good selectivity, repeatability and stable performance under ambient conditions. This work demonstrates an effective, low-cost structural engineering strategy to overcome the limitations of TMD-based gas sensors and highlights the potential of MoSe 2 for RT NO 2 sensing applications.