Preparation Of MoO3 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 200degreesC), 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, alpha-MoO3 lamellas with a thickness of similar to20-50 nm, and beta-MoO3 spheres of diameters down to nanometre scale can be synthesized at ambient atmosphere. These nanostructures exhibit a large optical band gap of similar to3.05 eV, and room-temperature photoluminescence at similar to395 nm. This study provides a simple, controllable way of fabricating metal oxide nanostructures of interest.