Oxalic acid mediated synthesis of WO3·H2O nanoplates and self-assembled nanoflowers under mild conditions

Tungsten oxide hydrate (WO3·H2O) nanoplates and flower-like assemblies were successfully synthesized via a simple aqueous method. The effects of reaction parameters in solution on the preparation were studied. Nanoplates and nanoflowers can be selectively prepared by changing the amount of H2C2O4. In-situ assembly of nanoplates to nanoflowers was also proposed for the formation of assembled nanostructures. In addition, the reaction time and temperature have important effects on the sizes of the as-obtained samples. Crystal structure, morphology, and composition of final nanostructures were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Optical properties of the synthesized samples and the growth mechanism were studied by UV–vis detection. Degradation experiments of Rhodamine B (RhB) were also performed on samples of nanoplates and nanoflowers under visible light illumination. Nanoflower sample exhibited preferable photocatalytic property to nanoplate sample.

Graphical abstractThe oxalic acid has a key role for the structure of WO3·H2O evolution from plates to flowers and the dehydration process of WO3·2H2O to WO3·H2O.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Tungsten oxides hydrate was synthesized via a simple aqueous method. ► The size of WO3·H2O was controlled by the reaction time and temperature. ► The assembly of WO3·H2O nanoplates to nanoflowers was achieved with higher H2C2O4/Na2WO4 ratio. ► Oxalic acid has a key role in the dehydration process of WO3·2H2O to WO3·H2O.