Architectural tailoring of orthorhombic MoO3 nanostructures toward efficient NO2 gas sensing

In the present study, an architectural tailoring strategy was established to tune crystalline orthorhombic molybdenum trioxide (α-MoO 3 ) to obtain nanostructures such as nanorods, dumbbell-shaped nanorods and hierarchical nanodisks for chemiresistive gas sensors. The different types of α-MoO 3 nanostructures were synthesized by adopting controlled hydrothermal reaction conditions such as reaction time and temperature. The morphological variation of nanostructures revealed changes in crystalline parameters, such as size, micro-strain, shape, surface area, and porosity. The microstructural effects and shape of the α-MoO 3 nanostructures were studied to determine their influence on the analytical characteristics of a gas sensor, the sensitivity, response time, and selectivity toward NO 2 analyte gas. The high surface area of α-MoO 3 nanorods showed a high sensitivity of 84% at an optimal operating temperature of 110 °C, with response and recovery times at 45 and 42 s, respectively, then dumbbell-shaped nanorods is reduced with 10% lower sensitivity than nanorods at 74% at a temperature of 130 °C. Nanodisks showed the least response compared to all the synthesized structures. All nanostructures of α-MoO 3 exhibited good selectivity for the NO 2 analytical gas with respect to interfering gases such as CO 2 , NH 3 , ethanol, methanol, and acetone and in addition, good stability and reproducibility have been observed.