A facile water-assisted route for synthesis of tungsten dioxide (WO2) nanopowders

The possibility of reducing the size of bulk materials, particularly making nanoparticles with controlled size, structure and shape offers massive benefits for various applications. In this respect, we report a novel water-assisted method to produce clusters of WO2 nanopowders with very high conversion yields of 90%. The proposed process is simplistic in its nature and carried out at room temperature. Nanopowders were obtained as a result of the hydrolysis of the tungsten precursor (WCl6) in the presence of NaBH4. Particle sizes of the as-synthesised partially crystallized nanopowders show a uniform distribution around 35 nm. Fully crystallized nanopowders without any morphological alteration were successfully produced already after annealing at 500 °C for 2 h. The nanopowders were examined using electron microscopy, XRD and DSC.