Preparation of MoO nanostructures and their optical properties

In this letter we report the synthesis of nanostructures of molybdenum trioxides by directly oxidizing a spiral coil of molybdenum, at ambient atmosphere, by passing a current through the coil. The advantage of this approach is that the temperature of the substrate is low (normally below 200 °C), and that the nanostructures to be formed could be chosen, via controlling the current or, equivalently, the temperature of the coil. We show that, by adjusting the current through the coil, α-MoO lamellas with a thickness of ∼20-50 nm, and β-MoO spheres of diameters down to nanometre scale can be synthesized at ambient atmosphere. These nanostructures exhibit a large optical band gap of ∼3.05 eV, and room-temperature photoluminescence at ∼395 nm. This study provides a simple, controllable way of fabricating metal oxide nanostructures of interest.