Ultrasonic synthesis of MoO3 nanorods and their gas sensing properties

Molybdenum oxide nanorods have been successfully synthesized by a simple probe ultrasonic approach. A possible growth mechanism of the MoO3 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-MoO3) and an irreversible phase transition occurs to form orthorhombic alpha-MoO3 after annealing at 436 degrees C. The gas sensing tests indicate that the MoO3 based sensor has high response to NO2 and the response is not interfered by CO and CH4 at operating temperature of 290 degrees C. The intrinsic sensing performance arises from the non-stoichiometry of MoO3 due to the presence of Mo5+ 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. (C) 2012 Elsevier B.V. All rights reserved.