A simple method of fabricating large-area α-MnO2 nanowires and nanorods

α-MnO2 nanowires or nanorods have been selectively synthesized via the hydrothermal method in nitric acid condition. The α-MnO2 nanowires hold with average diameter of 50 nm and lengths ranging between 10 and 40 μm, using MnSO4·H2O as manganese source; meanwhile, α-MnO2 bifurcate nanorods with average diameter of 100 nm were obtained by adopting MnCO3 as starting material. The morphology of α-MnO2 bifurcate nanorods is the first one to be reported in this paper. X-ray powder diffraction (XRD), field scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM) were used to characterize the products. Experimental results indicate that the concentrated nitric acid plays a crucial role in the phase purity and morphologies of the products. The possible formation mechanism of α-MnO2 nanowires and nanorods has been discussed.