Single-crystalline tungsten oxide nanoplates

Tungsten oxide nanocrystals are important semiconductor materials with a suitable energy band gap (ca. 2.5 eV) for visible-light utilization. Though there are a great amount of reports on the synthesis of WO₃ nanocrystals, no effective routes to two-dimensional (2D) WO₃ nanocrystals have been reported. We here developed a novel and efficient route to synthesize free-standing single-crystalline WO_s nanoplates on a large scale and in a repeatable way. The proposed route involved a rational transformation of tungstate-based inorganic-organic hybrid nanobelts to single-crystalline WO₃-H₂O nanoplates, and then to single-crystalline monoclinic WO₃ nanoplates with an inhibited crystal growth direction of [004]. The sizes of the as-obtained WO₃ nanoplates are (200-500) nm × (200-500) nm × (10-30) nm. The WO ₃ nanoplates as-synthesized have high specific surface areas (up to 180 m₂ g^-1) and showed remarkably enhanced visible-light photocatalytic properties in water splitting for O₂ generation.