Synthesis of WO₃ nanostructures and their ultraviolet photoresponse properties

Tungsten oxide (WO₃) nanostructures such as nanowires, nanorod bundles and nanotube bundles are synthesized by a facile hydrothermal method. The ultraviolet (UV) photoresponse characteristics of devices containing these WO₃ nanostructures are investigated for the first time and new photosensitive mechanisms involving both photo-generated electron-hole pairs and reversible electrochemical reactions are proposed. We find that h-WO ₃ nanowires with large specific surface areas and fewer defects exhibit excellent UV photoresponse properties with switch ratios (defined as I_photo/I_dark) as high as 60, which is due to the existing large tunnels serving as channels and intercalation sites for mobile ions and active electrochemical reactions, and our findings provide a new family and more selectivity for UV photosensitive nanomaterials in the future.