Template-free low temperature hydrothermal synthesis and characterization of rod-shaped manganese oxyhydroxides and manganese oxides

Single-crystalline MnOOH (gamma-MnOOH) and MnO2 nanorods (beta-MnO2 and alpha-MnO2) were synthesized by redox reaction of a mixture of KMnO4 and Mn(CH3COO)(2) at various pH levels at a temperature range of 120-180 degrees C. The products were characterized by powder x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), Raman and infra-red spectroscopy, field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). It is interesting to find that the prepared MnOOH and MnO2 all have one-dimensional nanostructures. The catalytic activity of MnO2 nanorods was studied for selective catalytic sulfur oxidation of model diesel containing 4,6-dimethyl dibenzothiophene in the presence of air as oxidant.