Size- And shape-controlled conversion of tungstate-based inorganic-organic hybrid belts to WO₃ nanoplates with high specific surface areas

Two-dimensional monoclinic WO₃ nanoplates with high specific surface areas are synthesized through a novel conversion process using tungstate-based inorganic-organic hybrid micro/nanobelts as precursors. The process developed involves a topochemical transformation of tungstate-based inorganic-organic hybrid belts into WO₃ nanoplates via an intermediate product of H₂WO₄ nanoplates, utilizing the similarity of the W-O octahedral layers in both H₂ WO₄ and WO₃. The as-obtained WO₃ nanoplates show a single-crystalline nanostructure with the smallest side along the [001] direction. The WO₃ nanoplates are 200-500 nm × 200-500 nm × 10-30nm in size, and their specific surface areas are up to 180 m ² g^-1. Photocatalytic measurements of visible-light-driven oxidation of water for O₂ generation in the presence of Ag ⁺ ions indicate that the activity of the as-obtained WO₃ nanoplates is one order of magnitude higher than that of commercially available WO₃ powders.