Hydrothermal preparation of nanostructured MnO and morphological and crystalline evolution

Abstract

Manganese dioxides with various morphologies were prepared using a common hydrothermal method without any templates or additives. The evolution of the morphology was accompanied by the gradual conversion of the polymorphic forms from ?-type to ?-type. Meanwhile, MnO₂ microspheres, urchin-like nanostructures and nanowires were successfully synthesized. The products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope and transmission electron microscope. The evolution process can be explained by the Ostwald Ripening mechanism.

Keywords

MnO₂ / hydrothermal preparation / crystal type / core-shell structure / nanowires