Ultrasonic synthesis of MoO3 nanorods and their gas sensing properties

Abstract

Abstract Molybdenum oxide nanorods have been successfully synthesized by a simple probe ultrasonic approach. A possible growth mechanism of the MoO 3 nanorods and the influence of ultrasonic times on morphologies have been investigated. The characterization results of field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and differential thermal analysis (DTA) demonstrate that the nanorods exhibits hexagonal molybdenum oxide ( h -MoO 3 ) and an irreversible phase transition occurs to form orthorhombic α-MoO 3 after annealing at 436 °C. The gas sensing tests indicate that the MoO 3 based sensor has high response to NO 2 and the response is not interfered by CO and CH 4 at operating temperature of 290 °C. The intrinsic sensing performance arises from the non-stoichiometry of MoO 3 due to the presence of Mo 5+ ions in the lattice of oxide, which has been confirmed by the results of X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) analysis.