Solvothermal Synthesis of Tungsten Oxide Nanorod/Nanowire/Nanosheet

A simple process enables to synthesize tungsten oxide with various nanomorphologies, i.e. nanorods, nanowires, and nanosheets. The tungsten hexachloride (WCl 6 ) was used as a raw material and the tungsten oxide nanoparticles were obtained by solvothermal treatment with solvents, i.e., ethanol, mixed solvent (ethanol+water), and water, at 200°C for 10 h. The various crystalline phases of tungsten oxide, such as monoclinic W 18 O 49 nanorods, hexagonal WO 3 platelets, and monoclinic WO 3 nanosheets, were synthesized by simply changing the composition of the solvent. The oxygen, which was contained in water, played an important role in the final tungsten oxide phase. Especially, W 18 O 49 nanorods grew to nanowires as the concentration of WCl 6 was decreased. Using this simple process, it will be possible to control the crystalline phase and morphologies of nanostructured tungsten oxide system.