A simple method to synthesise single-crystalline manganese oxide nanowires

Single-crystalline nanowires of hexagonal γ-MnO2 phase have been prepared by a simple method in which the commercial granular γ-MnO2 powders were hydrothermally treated in water or ammonia solution at 120–160 °C. The diameters of the γ-MnO2 nanowires are 5–50 nm and the lengths up to several tens of micrometers. Calcination of γ-MnO2 nanowires at the temperature range of 400–500 °C and above 600 °C results in, respectively, the production of single phases of β-MnO2 and α-Mn2O3 crystals, while the nanofibrous morphologies persist. These 1-D nanostructured manganese oxides are expected to have possible novel properties and wide applications.