Facile hydrothermal synthesis of MoO3 nanosheets for trace level ammonia detection at room temperature

Abstract

In the present work, α-MoO₃ nanostructures are synthesized via a one-step hydrothermal route using citric acid monohydrate as the surfactant, followed by calcination at a temperature of 400 °C for 3 h. The morphological, structural, compositional and optical properties of the synthesized material are thoroughly investigated using state-of-the-art facilities. XRD analysis confirmed the existence of an orthorhombic α-MoO₃ phase, and the peak at (021) confirms the formation of a lamellar structure, as observed in FESEM. A wide band gap of 4.9 eV is observed for MoO₃ nanosheets; this band gap is attributed to the quantum confinement effect and is further analyzed using density functional theory (DFT). The nanosheets formed with a layered structure provide a larger surface for active sites, and they show excellent sensitivity of 4.55 during the low-level detection (1 ppm) of ammonia vapour at room temperature, making them worth exploring as an excellent room-temperature ammonia sensor.