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 WO3 nanoplates on a large scale and in a repeatable way. The proposed route involved a rational transformation of tungstatebased 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 WO3 nanoplates as-synthesized have high specific surface areas (up to 180m2 g−1) and showed remarkably enhanced visible-light photocatalytic properties in water splitting for O2 generation.

Keywords: Tungsten oxide nanoplates, Tungstate nanoplates, Two-dimensional nanostructures, Inorganic-organic hybrids, Layered compounds.